Update tsconfig file to include .tsx files

[nina-py]

Refs #3533

Doesn't really fix the umbrella issue but is related to it.

Changes proposed in this pull request:
Change tsconfig.json so that project-specific configuration is taken into account not just for .ts files but for .tsx files as well. Removing the file extension makes TS default to processing just .ts, .tsx, and .d.ts. files.

Confirmed

• Frontend changes: tested on a local Flarum installation.

Required changes:

• Related documentation PR: (Remove if irrelevant)
• Related core extension PRs: (Remove if irrelevant)

[dsevillamartin]

I edited the description so the issue isn't closed if we merge this PR.

[askvortsov1]

This feels quite broad, essentially saying any file in src. Couldn't this cause files unrelated to JS/TS/TSX to be recognized incorrectly?

[nina-py]

@askvortsov1, according to the official documentation, this will actually do what we want it to do - parse only TypeScript files:

If a glob pattern doesn’t include a file extension, then only files with supported extensions are included (e.g. .ts, .tsx, and .d.ts by default, with .js and .jsx if allowJs is set to true).
https://www.typescriptlang.org/tsconfig#include

Since allowJs is not explicitly set to true, this change will mean that TS will go from parsing just .ts files to .ts, .tsx, and d.ts, ignoring JS files and anything else that may be present in those directories.

[nina-py]

Thanks for approving this @askvortsov1. I was thinking that perhaps it would be better to set the files to parse explicitly instead of following the TS docs - that way this config value would essentially become self-documenting:

"include": ["src/**/*.ts", "src/**/*.tsx"],

[askvortsov1]

Ah yes that's even better!

[nina-py]

@askvortsov1 done!