, bitcoin#29372, bitcoin#29460, bitcoin#29358, bitcoin#29511, bitcoin#29390, bitcoin#29431, bitcoin-core/gui#788 (BIP324 backports: part 4)

4735b82 merge bitcoin#29431: disconnection scenarios during v2 handshake (Kittywhiskers Van Gogh)
cc6b88e merge bitcoin-core/gui#788: update session ID tooltip (Kittywhiskers Van Gogh)
2455862 merge bitcoin#29390: speedup bip324_cipher.py unit test (Kittywhiskers Van Gogh)
062aaf1 merge bitcoin#29511: Fix intermittent failure in rpc_net.py --v2transport (Kittywhiskers Van Gogh)
54972e8 merge bitcoin#29358: use v2 everywhere for P2PConnection if --v2transport is enabled (Kittywhiskers Van Gogh)
4cce72f test: add missing debug log assertion in `p2p_invalid_messages.py` (Kittywhiskers Van Gogh)
bd2fe61 merge bitcoin#29460: assert rpc error for addnode v2transport not enabled (Kittywhiskers Van Gogh)
5ee15fa merge bitcoin#29372: fix intermittent failure in `rpc_setban.py --v2transport` (Kittywhiskers Van Gogh)
e278818 merge bitcoin#29352: fix intermittent failure in p2p_v2_earlykeyresponse (Kittywhiskers Van Gogh)
6b2a8b5 merge bitcoin#24748: functional tests for v2 P2P encryption (Kittywhiskers Van Gogh)
32500f2 merge bitcoin#27653: add unit test coverage for Python ECDSA implementation (Kittywhiskers Van Gogh)
9f476c6 net: add Dash network message short IDs, allocate range 128 onwards (Kittywhiskers Van Gogh)

Pull request description:

  ## Additional Information

  * Depends on #6329

  * Dash-specific P2P messages have been allocated short IDs after 128 based on a prior suggestion ([source](#6280 (comment))) as there are 255 potential short IDs (ID `0` is reserved for V1 fallback, [source](https://github.com/dashpay/dash/blob/a7bbcc823d800b293e9ec54dff518fa9929c763c/src/net.cpp#L1019)) and upstream uses 28 short IDs (though Dash has left ID `5` blank as we do not implement the `FEEFILTER` message, [source](https://github.com/dashpay/dash/blob/a7bbcc823d800b293e9ec54dff518fa9929c763c/src/net.cpp#L1024)).

    As it is unlikely that upstream will utilize more than 127 short IDs (and the spec refers to IDs after 32 as "undefined", [source](https://github.com/bitcoin/bips/blob/52894e1aa7af27f4ae7836a391643124c71e2639/bip-0324.mediawiki#v2-bitcoin-p2p-message-structure)), there shouldn't be an adverse effect to utilizing IDs >=128. The unified array of short IDs are accessible through `V2ShortIDs()`.

    * As there are checks to see if an ID *can* be valid by checking against the array size (which wouldn't work here as we create an array of 256 entries combining both upstream and Dash's allocated short IDs, filling the rest with blank values and we cannot ignore blank values to know if a value is unallocated as the blanking could also signal a reservation, [source](https://github.com/dashpay/dash/blob/a7bbcc823d800b293e9ec54dff518fa9929c763c/src/net.cpp#L1048-L1052)), such a check needs to be done by using `IsValidV2ShortID()`.
    * `V2ShortIDs()` isn't as elegant as desired as `std::fill` and `std::copy` are not `constexpr` until C++20 ([source](https://en.cppreference.com/w/cpp/algorithm/fill), [source](https://en.cppreference.com/w/cpp/algorithm/copy)) and until we drop C++17 support, we have to be mindful of that.

  * `masternode connect` will now _attempt_ to establish a P2Pv2 connection if the node *initiating* the connection has opted-in using the new argument (`v2transport`) and the node was started with P2Pv2 enabled (using the launch argument, `-v2transport`).

    This mirrors changes to behavior to `addconnection` introduced in [bitcoin#24748](bitcoin#24748)

  * The oversized payload test in `p2p_invalid_messages.py` will expect an excessively large message of size of `3145729` bytes (and in P2Pv2, `3145742` bytes), as opposed to upstream's `4000001` and `4000014` bytes respectively as Dash has a lower protocol limit of 3MiB ([source](https://github.com/dashpay/dash/blob/a7bbcc823d800b293e9ec54dff518fa9929c763c/src/net.h#L80-L81)) vs Bitcoin's 4MB ([source](https://github.com/bitcoin/bitcoin/blob/225718eda89d65a7041c33e1994d3bf7bd71bbdd/src/net.h#L62-L63))

  ## Breaking Changes

  None expected.

  ## Checklist:

  - [x] I have performed a self-review of my own code
  - [x] I have commented my code, particularly in hard-to-understand areas
  - [x] I have added or updated relevant unit/integration/functional/e2e tests
  - [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)_

ACKs for top commit:
  PastaPastaPasta:
    utACK 4735b82
  UdjinM6:
    light ACK 4735b82

Tree-SHA512: 4a9d586133633c109e6a8f20a6c6c5e4b24185fb616bcd8568e546b6e9f886e7a8707e811fd070bbe32c40df269f89a56343a24b67242c6147f9df27275af599