Ignore type-only entries in paths TypeScript compiler option

[niklashigi]

Based on #2070 (comment)

Currently, ESBuild uses TypeScript's paths compiler option to resolve source files which can lead to problems if the said option is only used to fix typing-related issues. That's because in those cases the destination paths will be .d.ts files which either result in parsing issues or the package not being imported (because the file is handled like an empty file).

Reproduction

The issue can be reproduced by cloning this repo, installing the dependencies, and then running the bundle and bundle:paths scripts. Right now the latter will fail because this fix isn't released yet. Once it is released it will no longer fail, but produce incorrect output as the bundle will no longer include the imported package (just void 0).

Possible fix

This could be fixed by ignoring all types entries ending in .d.ts as developers will never expect those to actually resolve to a source file at build time.

/cc @magic-akari

[magic-akari]

I am willing to fix it.