follow-up to bitcoin#28008.
* move `dummy_tag` variable in FSChaCha20Poly1305 crypto_tests
outside of the loop to be reused every time
* use easy to read `cipher.last()` in `AEADChaCha20Poly1305::Decrypt()`
* comment for initiator in `BIP324Cipher::Initialize()`
* systematically damage ciphertext with bit positions in bip324_tests
* use 4095 max bytes for aad in bip324 fuzz test

93cb8f0 refactor: add missing headers for BIP324 ciphersuite (stratospher)
d22d5d9 crypto: BIP324 ciphersuite follow-up (stratospher)

Pull request description:

  follow-up to #28008.
  * move `dummy_tag` variable in FSChaCha20Poly1305 crypto_tests outside of the loop to be reused every time
  * use easy to read `cipher.last()` in `AEADChaCha20Poly1305::Decrypt()`
  * comment for initiator in `BIP324Cipher::Initialize()`
  * systematically damage ciphertext with bit positions in bip324_tests
  * use 4095 max bytes for `aad` in bip324 fuzz test

ACKs for top commit:
  fanquake:
    ACK 93cb8f0 - thanks for following up here.

Tree-SHA512: 361f3e226d3168fdef69a2eebe6092cfc04ba14ce009420222e762698001eaf8be69a1138dab0be237964509c2b96a41a0b4db5c1df43ef75062f143c5aa741a

93cb8f0 refactor: add missing headers for BIP324 ciphersuite (stratospher)
d22d5d9 crypto: BIP324 ciphersuite follow-up (stratospher)

Pull request description:

  follow-up to bitcoin#28008.
  * move `dummy_tag` variable in FSChaCha20Poly1305 crypto_tests outside of the loop to be reused every time
  * use easy to read `cipher.last()` in `AEADChaCha20Poly1305::Decrypt()`
  * comment for initiator in `BIP324Cipher::Initialize()`
  * systematically damage ciphertext with bit positions in bip324_tests
  * use 4095 max bytes for `aad` in bip324 fuzz test

ACKs for top commit:
  fanquake:
    ACK 93cb8f0 - thanks for following up here.

Tree-SHA512: 361f3e226d3168fdef69a2eebe6092cfc04ba14ce009420222e762698001eaf8be69a1138dab0be237964509c2b96a41a0b4db5c1df43ef75062f143c5aa741a

, bitcoin#28267, bitcoin#28374, bitcoin#28100 (p2p primitives)

b60c493 merge bitcoin#28100: more Span<std::byte> modernization & follow-ups (Kittywhiskers Van Gogh)
c2aa01c merge bitcoin#28374: python cryptography required for BIP 324 functional tests (Kittywhiskers Van Gogh)
7c5edf7 merge bitcoin#28267: BIP324 ciphersuite follow-up (Kittywhiskers Van Gogh)
1b1924e merge bitcoin#28008: BIP324 ciphersuite (Kittywhiskers Van Gogh)
ff54219 merge bitcoin#27993: Make poly1305 support incremental computation + modernize (Kittywhiskers Van Gogh)
d7482eb merge bitcoin#27985: Add support for RFC8439 variant of ChaCha20 (Kittywhiskers Van Gogh)

Pull request description:

  ## Additional Information

  * Dependent on #5900

  * Dependent on #5901

  * Without modifications, tests introduced in [bitcoin#28008](bitcoin#28008) will fail due to salt comprising of a fixed string (`bitcoin_v2_shared_secret`) and network bytes ([source](https://github.com/sipa/bitcoin/blob/1c7582ead6e1119899922041c1af2b4169b0bc74/src/bip324.cpp#L39-L40)). Bitcoin uses [`{0xf9, 0xbe, 0xb4, 0xd9}`](https://github.com/sipa/bitcoin/blob/1c7582ead6e1119899922041c1af2b4169b0bc74/src/kernel/chainparams.cpp#L114-L117) for mainnet while Dash uses [`{0xbf, 0x0c, 0x6b, 0xbd}`](https://github.com/dashpay/dash/blob/37f43e4e56de0d510110a7f790df34ea77748dc9/src/chainparams.cpp#L238-L241).
    * The replacement parameters are generated by:
      * Cloning https://github.com/bitcoin/bips (as of this writing, at bitcoin/bips@b3701fa)
      * Editing `bip-0324/reference.py`
        * Changing `NETWORK_MAGIC` to Dash's network magic
      * Running `gen_test_vectors.py` to get a new `packet_encoding_test_vectors.csv`
      * Using [this python script](https://github.com/bitcoin/bitcoin/blob/1c7582ead6e1119899922041c1af2b4169b0bc74/src/test/bip324_tests.cpp#L174-L196) mentioned in a comment in `src/test/bip324_tests.cpp`, generate the values that will be used to replace the ones in `bip324_tests.cpp` (it will print to `stdout` so it's recommended to pipe it to a file)
      * Paste the new values over the old ones

  ## Breaking Changes

  None. Changes are restricted to BIP324 cryptosuite, tests and associated logic.

  ## Checklist:
    _Go over all the following points, and put an `x` in all the boxes that apply._
  - [x] I have performed a self-review of my own code
  - [x] I have commented my code, particularly in hard-to-understand areas **(note: N/A)**
  - [x] I have added or updated relevant unit/integration/functional/e2e tests **(note: N/A)**
  - [x] I have made corresponding changes to the documentation **(note: N/A)**
  - [x] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

Top commit has no ACKs.

Tree-SHA512: bb056de8588026adae63e78d56878274ff3934a439e2eae81606fa9c0a37dab432a129315bb9c1b754400b5c883bf460eea3a0c857a3be0816c8fbf55c479843

8607773 Add fuzz test for FSChaCha20Poly1305 (stratospher)
c807f33 Add fuzz test for AEADChacha20Poly1305 (stratospher)

Pull request description:

  This PR adds fuzz tests for `AEADChaCha20Poly1305` and `FSChaCha20Poly1305` introduced in #28008.

  Run using:
  ```
  $ FUZZ=crypto_aeadchacha20poly1305 src/test/fuzz/fuzz
  $ FUZZ=crypto_fschacha20poly1305 src/test/fuzz/fuzz
  ```

ACKs for top commit:
  dergoegge:
    tACK 8607773
  marcofleon:
    Tested ACK 8607773. Ran both targets for ~200 CPU hours. Coverage of intended targets looks good to me. The simulation of damaged keys and checks that follow seem useful as well.

Tree-SHA512: b6b85661d896e653caeed330f941fde665fc2bbd97ecd340808a3f365c469fe9134aa77316569a771dc36d1158cac1a5f76700bcfc45fff12aef07562e48feb9