feat(tsconfig-loader): extends config from node_modules

[zorji]

At the moment, when an extends path is specified, the extends path has to be relative to the overriding tsconfig.json file.

However, in the implementation of tsc --showConfig, it also supports search from node_modules in the same current directory.

e.g.

If a base file exists in node_modules/my-package/tsconfig.base.json.

Both

{
  "extends": "./node_modules/my-package/tsconfig.base.json"
}

and

{
  "extends": "my-package/tsconfig.base.json"
}

have the same effect.

Because tsc behaves like this, tsconfig-paths should be consistent.

[codecov]

Codecov Report

Merging #106 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #106   +/-   ##
=====================================
  Coverage       0%     0%           
=====================================
  Files           4      4           
  Lines         129    129           
  Branches       52     52           
=====================================
  Misses        129    129

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[yusufkandemir]

Look good to me, tested it locally and confirm that it works as expected 🚀 Thanks, @zorji. @Jontem @jonaskello kind ping to remind about the existence of this PR.

[jonaskello]

Ok let's merge this :-)

[jonaskello]

Released in 3.10.0.

[zorji]

I am using this change but I found that it's still broken for eslint because I also need to fix match-path-* (used by eslint-import-typescript).

I'll create a PR later today or tomorrow.

@johankristiansson @yusufkandemir