[K8s]: refactor the codes

[wanyunSu]

Description

Fixes #759 , #758

1. Improve the logic for identifying whether a pod acts as a local connection server using boot request information instead of pm config.
2. Improve the logic for identifying whether a pod acts as a root controller.
3. Add documentation.

Type of change

• Documentation (non-breaking change that adds or improves the documentation)
• New feature (non-breaking change which adds functionality)
• Optimization (non-breaking, back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (whatever its nature)

Key checklist

• All tests pass (eg. python -m pytest)
• Pre-commit hooks run successfully (eg. pre-commit run --all-files)

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added or an issue has been opened to tackle that in the future.
  (Indicate issue here: # (issue))

[PawelPlesniak]

This is a good start, but therre are several missing arguments and return types. Can we have them for all the functions

[PawelPlesniak]

Will scan through, update any missing type signatures, improve missing docs, and do some basic commenting throughout the code. Generally to start the documentation is much better.