Don't allow to create suggestions from PR diff (#6623)

Part of #6603

Author: alexr00

src/commands.ts

@@ -1218,6 +1218,10 @@ ${contents}
 			return vscode.window.showErrorMessage(vscode.l10n.t('Current editor isn\'t a diff editor.'));
 		}
 
+		if (input.original.scheme !== Schemes.Git) {
+			return vscode.window.showErrorMessage(vscode.l10n.t('Converting changes to suggestions can only be done from a git diff, not a pull request diff'), { modal: true });
+		}
+
 		const editor = vscode.window.visibleTextEditors.find(editor => editor.document.uri.toString() === input.modified.toString());
 		if (!editor) {
 			return vscode.window.showErrorMessage(vscode.l10n.t('Unexpectedly unable to find the current modified editor.'));

src/common/uri.ts

@@ -514,7 +514,8 @@ export enum Schemes {
 	MergeOutput = 'merge-output', // Merge output
 	Notification = 'notification', // Notification tree items in the notification view
 	NewIssue = 'newissue', // New issue file
-	Repo = 'repo' // New issue file for passing data
+	Repo = 'repo', // New issue file for passing data
+	Git = 'git', // File content from the git extension
 }
 
 export function resolvePath(from: vscode.Uri, to: string) {