Following Jan-Simon's suggestion, build-sdks-json.sh script must be rewritten to support any releases ("release//**") 

See aborted review for more info:
https://gerrit.automotivelinux.org/gerrit/c/src/xds/xds-server/+/22504

More globally, this script must run each time xds-server startup (or triggered by an API of xds-server) in order to refresh SDKs list at any time.

To do that we need a way to easily retrieve list SDKs and detailed information of each SDKs. For now there is no way to find such information easily (time consuming > 2min and non robust implementation).