fix(cli): panic with deno coverage

[0xIchigo]

This PR directly addresses the issue raised in #23282 where Deno panics if deno coverage is called with --include regex that returns no matches.

I've opted not to change the return value of collect_summary for simplicity and return an empty HashMap instead

[bartlomieju]

Thanks for the PR, could you please add a test case that exercises this change? You can add an itest! check in tests/integration/coverage_tests.rs