feat: add support for test assertions and updating test cases

[gouravkrosx]

Related Issue

• Add support for absolute matching of test cases covering not only a response but a complete file comparison.

Closes: #1369

Describe the changes you've made

• Add a method to update a particular test case
• Add function for absolute comparison between two test cases.
• Add some nil checks so that Exported functions of yamlstore can be used from outside.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, local variables)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Describe if there is any unusual behaviour of your code(Write NA if there isn't)

NA

Checklist:

• My code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.

Screenshots (if any)

Original	Updated
original screenshot	updated screenshot

[re-Tick]

Ship it