Add MeloZen Bidder Adapter for Prebid Server

[benben2001]

This pull request introduces a new bidder adapter called "MeloZen" for Prebid Server.

[github-actions[bot]]

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, d2cddf81e52c8448322797bc610328e1ce4636ac

  melozen

  Refer here for heat map coverage report

  github.com/prebid/prebid-server/v2/adapters/melozen/melozen.go:23:  Builder             100.0%
  github.com/prebid/prebid-server/v2/adapters/melozen/melozen.go:36:  MakeRequests            64.1%
  github.com/prebid/prebid-server/v2/adapters/melozen/melozen.go:103: buildEndpointURL        100.0%
  github.com/prebid/prebid-server/v2/adapters/melozen/melozen.go:108: MakeBids            82.6%
  github.com/prebid/prebid-server/v2/adapters/melozen/melozen.go:153: splitImpressionsByMediaType 87.5%
  github.com/prebid/prebid-server/v2/adapters/melozen/melozen.go:181: getMediaTypeForBid      83.3%
  total:                                  (statements)            76.9%