Setup `contrib/` directory with CODEOWNERS that is extensible for non-SDK team extensions. #2544

Job	Run time
Unit test with in-memory test service [Edge]	33s
Unit test with cloud	31s
Unit test with docker service [JDK8]	49s
Code format	31s
Javadoc	36s
Build native test server / Build native test server (ubuntu-latest, linux, amd64, true)	2m 3s
Build native test server / Build native test server (macos-15-intel, macOS, amd64)	1m 6s
Build native test server / Build native test server (ubuntu-24.04-arm, linux, arm64)	2m 20s
Build native test server / Build native test server (macos-latest, macOS, arm64)	59s
Build native test server / Build native test server (ubuntu-latest, linux, amd64, false)	2m 8s
Build native test server / Build native test server (windows-latest, windows, amd64)	1m 16s
	12m 52s

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