fix(cli): emits error if no target files are found

[magurotuna]

This PR makes fmt and lint emit "No target files found." error if no target files are found. (This happens if the passed path is URL, for example.)
Fixes #9518

[caspervonb]

Hmmm I don't think we should change the behaviour of collect_files but instead if should be up to the individual commands?

The test command for example has an option to allow no test files to be run (deno test --allow-none) and I am making use of collect_files in my experimental test-runner.

I think the call site tools::lint::lint_files would be a good place to error out for example.

[magurotuna]

@caspervonb Okay that makes sense. I'll revert collect_files and move checking for validity of target paths to lint_files and fmt where collect_files is called.

[ry]

Thank you - LGTM

[caspervonb]

LGTM