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

[James Henderson via llvm-commits]

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@@ -0,0 +1,83 @@
+# Check cat command with single file.
+#
+# RUN: rm -rf %T/testCat
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jh7370 wrote:

`%t` is equivalent to `%T/<unique name derived from the test source file name>`. It's just a full path that is unique to the test, so can be used either as a directory (in which case you should delete it and recreate it at the start of the test), or as the basis of a filename or some other option (as well as simply using `%t` directly, other common example usages are `%t.o` for a path to an object file unique to the test, or `%t/a/b` to create a directory tree a/b inside a directory at `%t`. Does that make sense?

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