Auto merge of #50750 - est31:master, r=eddyb
Remove ScopeTarget and LoopIdResult
* Remove ScopeTarget in preparation of label-break-value (PR #50045)
* Replace LoopIdResult by Result which is possible now thanks to commit 8ac65af81f5f9cf6c5e2c2306705b50eed77cfb5 " Implement Encodable and Decodable for Result."
r? @eddyb