fix: remove incremental compilation caches across builds (#466)
fix: remove incremental compilation caches across builds (#466)

Currently, consecutive builds of the extension will fail because
[TypeScript always saves](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-4.html#composite-projects)
incremental compilation information in a composite project like this
one. In particular, this means that even when the output directory of
the TS compilation is removed, TypeScript doesn't realize that the
output files are no longer there because it has cached the build graph,
and thus not all the expected files are present for copying to the
extension output directory.

This commit fixes the above issue by removing TypeScript's incremental
compilation build files before rebuilding the project.
angular/vscode-ng-language-service,angular/vscode-ng-language-service,angular/vscode-ng-language-service,angular/vscode-ng-language-service