[llvm] [Lit][NFC] Refactor shell environment functionality and in-process builtins from TestRunner.py into new modules (Reopened) (PR #177358)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `cross-project-tests-sie-ubuntu` running on `doug-worker-1a` while building `llvm` at step 6 "test-build-unified-tree-check-cross-project".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/181/builds/41934

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-cross-project) failure: test (failure)
...
    from lit import LitConfig, Test, util
  File "/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/llvm/utils/lit/lit/LitConfig.py", line 9, in <module>
    import lit.formats
  File "/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/llvm/utils/lit/lit/formats/__init__.py", line 7, in <module>
    from lit.formats.googletest import GoogleTest  # noqa: F401
  File "/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/llvm/utils/lit/lit/formats/googletest.py", line 10, in <module>
    import lit.TestRunner
  File "/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 662, in <module>
    ) -> tuple[str, str, int, str | None, str | None]:
TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'
FAILED: projects/cross-project-tests/CMakeFiles/check-cross-project /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/projects/cross-project-tests/CMakeFiles/check-cross-project 
cd /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/projects/cross-project-tests && /usr/bin/python3.8 /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/./bin/llvm-lit --verbose --timeout=900 /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu/build/projects/cross-project-tests
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/177358