Pubmatic Bid Adapter: Adding test cases (prebid#13525)

* adding test cases to increase code coverage of code

* Adding test case for outstrean video case handling

* Adding test cases

* adding test cases to increase the code coverage

* Adding test case for multiformatrequest

* removing unnecesssary imports

* Lint fix

* lint error fix

* lint error fix2

* lint error fix 2

* lint error fix 3

* lint error fix 4

* lint error fix 5

* lint error fix 6

* Fixing the issue after the master merge

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Co-authored-by: Tanishka Vishwakarma <tanishkavishwakarma@L1837.local>
Co-authored-by: Chris Huie <phoenixtechnerd@gmail.com>
Co-authored-by: Patrick McCann <pmccann@cafemedia.com>
Co-authored-by: Tanishka Vishwakarma <tanishkavishwakarma@L1837.Dlink>

Author: 5 people