Add gopl adapter, replace sspBC adapter

[wojciech-bialy-wpm]

• Add gopl adapter, with new vendor id (690).
• This will replace existing sspBC adapter (with vendor id 676).
• Adapter functionality has not changed.
• Add sspBC alias, for legacy compatibility
• sspBC adapter and its vendor will be phased out in Q4/2026

This is a complementary pull request to Prebid.js (see prebid/Prebid.js#15360) and prebid.github.io (see prebid/prebid.github.io#6667)

[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, 9ffcda4

gopl

Refer here for heat map coverage report

github.com/prebid/prebid-server/v4/adapters/gopl/gopl.go:37:	Builder			100.0%
github.com/prebid/prebid-server/v4/adapters/gopl/gopl.go:50:	MakeRequests		83.3%
github.com/prebid/prebid-server/v4/adapters/gopl/gopl.go:73:	MakeBids		100.0%
github.com/prebid/prebid-server/v4/adapters/gopl/gopl.go:112:	getBidType		100.0%
github.com/prebid/prebid-server/v4/adapters/gopl/gopl.go:129:	buildAdapterEndpoint	100.0%
total:								(statements)		97.7%