Add dshell tests for Issue 22816 and Issue 22817

[ibuclaw]

@MoonlightSentinel - Eventually worked out how to make it work.

[dlang-bot]

Thanks for your pull request, @ibuclaw!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✗	22816	regression	[REG 2.099] Parser reads files with other extensions

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "stable + dmd#13713"

[thewilsonator]

Seems to fail on Windows, possibly due to / vs \?

[ibuclaw]

Seems to fail on Windows, possibly due to / vs \?

That's what I thought, which is why I added .replace("/", SEP), and yet it still seems to fail.

[MoonlightSentinel]

grep interprets the arguments as a regex. I've added a small commit that works on windows