[llvm] [llvm-lit] Print environment variables when using env without subcommand (PR #98414)

[via llvm-commits]

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@@ -1,3 +1,5 @@
+## Tests the env command's ability to handle setting, unsetting, and mixing environment variables.
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Harini0924 wrote:

I agree `env-no-subcommand.txt` is a better file name. I have renamed `env-args-none.txt` to `env-no-subcommand.txt` in my recent commit. 

https://github.com/llvm/llvm-project/pull/98414