Auto merge of #13221 - Alexendoo:farewell-metadata-collector, r=xFrednet

Replace the metadata collector with tests

The metadata collector handles 3 files: [`CHANGELOG.md`](https://github.com/rust-lang/rust-clippy/blob/c082bc2cb85313901ed3565fcd285592ed93df0f/CHANGELOG.md#L6050), [`lint_configuration.md`](https://github.com/rust-lang/rust-clippy/blob/c082bc2cb85313901ed3565fcd285592ed93df0f/book/src/lint_configuration.md) and `util/gh-pages/lints.json`

- `CHANGELOG.md` and `lint_configuration.md` are now checked by `tests/config-metadata.rs`, when they are outdated `cargo test` will fail with a message to run `cargo bless --test config-metadata` in order to update them

   A plain `cargo bless` will run all the tests, blessing both this and the UI tests

- `util/gh-pages/lints.json` is now generated when running `cargo uitest` with `COLLECT_METADATA=1` (still aliased to `cargo collect-metadata`)

   It uses a `ui_test` [post test action](https://docs.rs/ui_test/latest/ui_test/custom_flags/trait.Flag.html#method.post_test_action) to retrieve the applicability from the actual diagnostics emitted during UI tests

   Example change from the current to new JSON:

   ```diff
      {
        "id": "chars_next_cmp",
   -    "id_span": {
   -      "path": "src/methods/mod.rs",
   -      "line": 891
   -    },
   +    "id_location": "clippy_lints/src/methods/mod.rs#891",
        "group": "style",
        "level": "warn",
   -    "docs": "\n### What it does ... ```",
   +    "docs": "### What it does ... ```\n",
        "version": "pre 1.29.0",
   -    "applicability": {
   -      "is_multi_part_suggestion": false,
   -      "applicability": "Unresolved"
   -    }
   +    "applicability": "MachineApplicable"
      },
   ```

   `Hide whitespace` makes the `compile-test.rs` changes much easier to see

r? `@flip1995`

changelog: none

0 files changed, 0 insertions, 0 deletions