Test/mocks: added mocks for test cases

[SohamRatnaparkhi]

Proposed changes

This PR adds mocks for:

• experiment mocks
• experiment run mocks
• infra mocks
• gitops mocks

It also fixes incorrect mongo operator used in operators

Summarize your changes here to communicate with the maintainers and make sure to put the link of that issue

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

• nil

Special notes for your reviewer:

This PR is related to LFX-Mentorship'23: Term2

[namkyu1999]

LGTM 👍