…` package and collect metrics

d154b2a refactor: [#1358] clean Swarm type (Jose Celano)
b3b0b71 refactor: [#1358] Swarm, cleaning upsert_peer method (Jose Celano)
47d1eab refactor: [#1358] Swarm tests to use new mock helpers (Jose Celano)
b13797e test: [#1358] add tests for events in torrent-repository pkg (Jose Celano)
f71211f test: [#1358] add tests to torrust_tracker_torrent_repository::swarms::Swarms (Jose Celano)
3d7e6ff test: [#1358] add tests to torrust_tracker_torrent_repository::swarm::Swarm (Jose Celano)
0e38707 fix: [#1358] revert Hash impl for Swarm (Jose Celano)
c9a893c refactor: [#1358] rename metrics for clarity (Jose Celano)
8ee258e refactor: [#1358] use the new field info-hash as ID for the Swarm (Hash,PartialEq) (Jose Celano)
dfba00c feat: [#1358] allow disabling the event sender in the torrent-repository pkg (Jose Celano)
60c00e8 feat: [#1358] add info-hash to all torrent-repository events (Jose Celano)
c706a1b refactor: [#1358] move logs (Jose Celano)
daba8a0 feat: [#1358] new metric in torrent-repository: total number of downloads (Jose Celano)
01a9970 feat: [#1358] new metric in torrent-repository: total number of peers (Jose Celano)
269d273 refactor: [#1358] rename metric (Jose Celano)
ba2033b fix: [#1358] trigger PeerRemoved event when peer is removed due to inactivity (Jose Celano)
d47483f feat: [#1358] new metric in torrent-repository: total number of torrents (Jose Celano)
29a2dfd dev: change default config (Jose Celano)
1eb545c feat: [#1358] remove persistent metric from torrent-repository pkg (Jose Celano)
6d95d1a refactor: [#1358] inject event sender in Swarm type (Jose Celano)
2c479a1 refactor: [#1358] inject event sender in Swarms type (Jose Celano)
68b930d feat: [#1495] expose new torrent-repositoru metrics via the REST API (Jose Celano)
41f4022 feat: [#1358] inject Swarms into InMemoryTorrentRepository in testing code (Jose Celano)
95766bb feat: [#1358] inject Swarms into InMemoryTorrentRepository in production code (Jose Celano)
f986bda feat: [#1358] add the  and run the event listener when the tracker starts (Jose Celano)
2522ad4 feat: [#1358] basic scaffolding for events in torrent-repository pkg (Jose Celano)

Pull request description:

  Emit events from the `torrent-repository package` and collect metrics. In this PR, I'm only planning to include four metrics. The ones we have in the current `stats` endpoint:

  ```json
  {
    "torrents": 387044,
    "seeders": 183887,
    "completed": 1260584,
    "leechers": 249136,
  }
  ```

  However, I will rename them to:

  ```
  {
    "torrent_repository_per_session_all_instances_all_torrents_total": 387044,
    "torrent_repository_per_session_all_instances_all_seeders_total": 183887,
    "torrent_repository_per_session_all_instances_all_torrents_downloads_total": 1260584,
    "torrent_repository_per_session_all_instances_all_leechers_total": 249136,
  }
  ```

  **UPDATE:** I will not use those long names but "labels". It's only to explain what they represent.

  - per session: since the main tracker process started.
  - all instances: all tracker servers (UDP or HTTP) running on different ports.
  - all torrents: all swarms.

  Becuase the current names are too ambiguous. See #1502 (comment).

  ### How to test

  1. Run the tracker.
  2. Use the tracker client to make an announce request.

    ```
    cargo run -p torrust-tracker-client --bin udp_tracker_client announce udp://127.0.0.1:6969 443c7602b4fde83d1154d6d9da48808418b181b6 | jq
    ```
  3. Use the REST API to get the metric value.

    ```
    curl -s "http://localhost:1212/api/v1/metrics?token=MyAccessToken&format=prometheus" | grep torrent_repository_peers_total
    ```

  ### Subtasks

  - [x] Add basic event scaffolding in the `torrent-respository` package.
  - [x] Run the event listener for the torrent-repository package when the tracker starts.
    - [x] Add the `TorrentRepositoryContainer` and run the listener when the tracker starts.
    - [x] In production code: use the `Swarms` service provided by the `TorrentRepositoryContainer` in the `TrackerCoreContainer` (otherwise they will be unrelated).
    - [x] In testing code: use the `Swarms` service provided by the `TorrentRepositoryContainer` in the `TrackerCoreContainer` (otherwise they will be unrelated).
  - [x] Expose the new metrics via the `metrics` API endpoint (even if it will have no value yet).
  - [x] Inject the event sender in `Swarms` and `Swarm` type to be able to send events from them.
    - [x] In `Swarms` type.
    - [x] In `Swarm` type.
  - [x] #1516
  - [x] Star triggering events and process them to update the metrics in the metrics collection. One event and the corresponding affected metrics at the time.
    - [x] `TorrentAdded` -> Increase torrents counter (all instances, all torrents)
    - [x] `Torrentremoved` -> Decrease torrents counter (all instances, all torrents)
    - [x] `PeerAdded` -> Increase peers counter (total, seeders, leechers)
    - [x] `PeerRemoved` -> Decrease peers counter (total, seeders, leechers)
    - [x] `PeerUdpated` -> Decrease peers counter (total, seeders, leechers)
    - [x] `PeerDownloadCompleted` -> Increase torrent downloads counter (all instances, all torrents)
  - [x] Add tests to check that events have been sent.
  - [x] Add tests to check that metrics are updated after receiving the event.

ACKs for top commit:
  josecelano:
    ACK d154b2a

Tree-SHA512: d4946847dae38b51bc6027b4de25d7e2ad5b1042294913008f503c590c81e586ed083ab980613d647a0f867601f7bd482f4c004628c01cdfffc9d8b810bb670e