Update directory name from MyHub to ChaosHub

[namkyu1999]

Proposed changes

To ensure the stability and long-term viability of our codebase, I suggest unifying the terms 'MyHub' to 'ChaosHub'.
And this PR update codes like below.

• Updating directory name(package name) from myhub to chaoshub
• Updating function names and variable names relevant to myhub
• Changing collection name of myhub to chaoshub in MongoDB
• Updating any related tests and documentation to reflect the changes made.

Issue No. #3927

Types of changes

What types of changes does your code introduce to Litmus? Put an x in the boxes that apply

• New feature (non-breaking change which adds functionality)
• Bugfix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices applies)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• I have read the CONTRIBUTING doc
• I have signed the commit for DCO to be passed.
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have added necessary documentation (if appropriate)

Dependency

• Please add the links to the dependent PR need to be merged before this (if any).
  Move to using interfaces for better mocking, abstraction and decoupling #3931

Special notes for your reviewer: @S-ayanide @amityt

[S-ayanide]

LGTM

[imrajdas]

@Jonsy13 please check this.