[llvm] [llvm-lit][test][NFC] Moved cat command tests into separate lit test file (PR #102366)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

What do you think about removing `shtest` from the test directory names? I'm not convinced about its value to the test description.

https://github.com/llvm/llvm-project/pull/102366