Add support for *.tidal files

`.tidal` is the standard extension for [TidalCycles](https://tidalcycles.org/) files. These are basically just a scratchpad containing Haskell expressions. You can then use the [vscode-tidalcycles](https://github.com/kindohm/vscode-tidalcycles) extension to feed these expressions into GHCi.

To get syntax highlighting at the moment, one has to associate `*.tidal` files with the `Haskell` filetype, but this causes other extensions like [haskell-lsp](https://github.com/alanz/haskell-lsp) to go a bit nuts because they expect the files to be valid Haskell modules.

P.S. If you think it is better to put this in its own extension I'll do that.

Proposal:

```
"languages": [
...
{
"id": "tidal",
"aliases": [
"Tidal",
"tidal"
],
"extensions": [
".tidal"
],
"configuration": "./haskell-configuration.json"
}
],
```

Start by locating the extension's language registration and compare the proposed `tidal` entry with the existing Haskell configuration. Add `.tidal` recognition and verify that Tidal files receive syntax highlighting without being treated as Haskell modules by language tooling.

Written by the indexing model from the issue text.