Medianet: Add fledge support

[bhavye-g]

Add Fledge support for Medianet adapter. The response from bidder for fledge auction config support the ortb format mentioned in the below link.
https://github.com/InteractiveAdvertisingBureau/openrtb/blob/main/extensions/community_extensions/Protected%20Audience%20Support.md

Previously opened MR that got closed because developer account was removed
#3641

[github-actions]

Code coverage summary

Note:

• Prebid team doesn't anticipate tests covering code paths that might result in marshal and unmarshal errors
• Coverage summary encompasses all commits leading up to the latest one, 858444f

medianet

Refer here for heat map coverage report

github.com/prebid/prebid-server/v2/adapters/medianet/medianet.go:43:	MakeRequests		75.0%
github.com/prebid/prebid-server/v2/adapters/medianet/medianet.go:64:	MakeBids		85.7%
github.com/prebid/prebid-server/v2/adapters/medianet/medianet.go:113:	Builder			100.0%
github.com/prebid/prebid-server/v2/adapters/medianet/medianet.go:121:	getMediaTypeForImp	85.7%
github.com/prebid/prebid-server/v2/adapters/medianet/medianet.go:137:	extractFledge		100.0%
github.com/prebid/prebid-server/v2/adapters/medianet/medianet.go:162:	buildEndpoint		88.9%
total:									(statements)		87.9%

[onkarvhanumante]

@bhavye-g PR tests are failing with following error. Should rectify it to proceed with code reviews

ok  	github.com/prebid/prebid-server/v2/adapters/lunamedia	0.027s	coverage: 89.9% of statements
ok  	github.com/prebid/prebid-server/v2/adapters/mabidder	0.026s	coverage: 95.2% of statements
ok  	github.com/prebid/prebid-server/v2/adapters/madvertise	0.029s	coverage: 90.0% of statements
ok  	github.com/prebid/prebid-server/v2/adapters/marsmedia	0.026s	coverage: 74.3% of statements
--- FAIL: TestJsonSamples (0.00s)
    test_json.go:130: medianettest/exemplary/fledge.json: MakeBids had wrong error count. Expected 0, got 1 ([Unable to fetch mediaType for imp: 1])
FAIL
coverage: 76.8% of statements
FAIL	github.com/prebid/prebid-server/v2/adapters/medianet	0.027s
FAIL