Fixes#26295
There are several places where we have accidentally added new license headers with linters but failed to remove old license headers manually. This prevents that by applying the an inverted version of the license headers rule that removed invalid license headers when files are moved.
Just like our ESLint rules, I think we should enforce named exports over default exports via TSLint. No changes to the code were necessary because of this linting rule because everyone is already following the pattern we established with ESLint, but TSLint wasn't actually verifying the pattern.
In order to make the license that applies to each file as clear as possible, and to be consistent with elasticsearch, we are adding Apache 2.0 license headers to the top of each file.
Existence of this header is enforced by eslint and tslint and missing headers were automatically added in the last commit by running:
```
node scripts/eslint --fix && node scripts/tslint --fix
```
* [tslint] lint typescript code
* [tslint] filter projects when running specific project
* [dev/ts] use more explicit types
* [dev/ts] add note about why using glob
* [dev/ts] rely on ts, use fewer getters
