Set `files` field in all of our `package.json` files

[rauno56]

files field defines which files ought to be included in the final published package.

• set files for all the package.json files. Don't include files always included, remove non-existing doc, TS source files. Basically only .js, .js.map and .d.ts files in the build folder need to be included,
• remove .npmignore files since it doubles files as an blacklist.

Motivation:

• Users may experience issues with tsconfig.json being included: auto-instrumentations-node - File '../../tsconfig.base' not found. #733
• Package sizes could be a lot smaller - excluding build/tsconfig.tsbuildinfo would halve the package size for @opentelemetry/auto-instrumentations-node

[dyladan]

Existence of this field seems like something that could easily be checked in CI

[rauno56]

Existence of this field seems like something that could easily be checked in CI

Yes, that's a good idea! Plus points for adding that for whoever will take this.

[macno]

ready to pick this one #contribfest