clang-format: [JS] pragmas for tslint, tsc.

clang-format: [JS] pragmas for tslint, tsc.

Summary:
tslint and tsc (the TypeScript compiler itself) use comment pragmas of
the style:

  // tslint:disable-next-line:foo
  // @ts-ignore

These must not be wrapped and must stay on their own line, in isolation.
For tslint, this required adding it to the pragma regexp. The comments
starting with `@` are already left alone, but this change adds test
coverage for them.

Reviewers: krasimir

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D72907