[Test] Use WARNING_QUIT instead of exit, Add and refactor unittests for ParaGlobal

[Cstandardlib]

Linked PR

#6771

Unit Tests and/or Case Tests for my changes

• Add ParaGlobalDeathTest for Parallel_Global, specifically for error-exit cases.
• Add tests for kpar check in Parallel_Global with WARNING_QUIT.
• Use a single process for DeathTest.

What's changed?

• TEST: Use GoogleTest DeathTest convension.
• Write Error/Warning message to stdout and check by redirecting stdout to stderr in test context to be captured by gtest EXPECT_EXIT.

Any changes of core modules? (ignore if not applicable)

• Switch to WARNING_QUIT instead of exit if the input parallel group does not meet expectations.

Note

Note that WARNING_QUIT writes warning/error log to stdout.