Support ${issueType} in githubIssues.issueBranchTitle#8712

Copilot wants to merge 2 commits intomainmicrosoft/vscode-pull-request-github:mainfrom

copilot/support-issue-type-template-variablemicrosoft/vscode-pull-request-github:copilot/support-issue-type-template-variableCopy head branch name to clipboard