[Parse] Refactor Lexer's skipToEndOfline

[omochi]

Lexer has two similar methods which are skipToEndOfLine and skipUpToEndOfLine.

This PR unify them.

The only difference in them are that
it will stop at which before or after of newline found,
so add EatNewline parameter to function to control this.

And because of this behavior about newline,
lexTrivia does not reuse skipSlashSlashComment and skipHashbang.
So add EatNewline to them, use in common from lexTrivia

This PR includes my other PR #13483

[harlanhaskins]

@swift-ci please smoke test

[rintaro]

@omochi Could you rebase this PR?

[omochi]

@rintaro OK, I will do.

[omochi]

I rebased and tested it locally.

[rintaro]

Thanks!
@swift-ci Please smoke test