Feat: added .css() and .getCssValue() as an alias for .getCssProperty()

[Ayush-Vish]

fixes #4167

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[Ayush-Vish]

Done all the required changes for this Pr as Well

[garg3133]

Please fix the merge conflict in this PR.

[garg3133]

Please move these test cases to their respective places. And if you see clearly, the test case for .css() is already present in the file.

[garg3133]

Looks good, thanks!

[Ayush-Vish]

Looks good, thanks!

Thankyou.