SCM - plumbing to support artifacts in the repositories view (#274173)

* WIP - ported changes from the old branch

* More work getting the changes ready

* Tweak things

* Git - wire-up checkout command

extensions/git/src/artifactProvider.ts

@@ -0,0 +1,62 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { LogOutputChannel, SourceControlArtifactProvider, SourceControlArtifactGroup, SourceControlArtifact, Event, EventEmitter, ThemeIcon, l10n, workspace, Uri } from 'vscode';
+import { IDisposable } from './util';
+import { Repository } from './repository';
+
+export class GitArtifactProvider implements SourceControlArtifactProvider, IDisposable {
+	private readonly _onDidChangeArtifacts = new EventEmitter<string>();
+	readonly onDidChangeArtifacts: Event<string> = this._onDidChangeArtifacts.event;
+
+	private readonly _groups: SourceControlArtifactGroup[];
+
+	constructor(
+		private readonly repository: Repository,
+		private readonly logger: LogOutputChannel
+	) {
+		this._groups = [
+			{ id: 'branches', name: l10n.t('Branches'), icon: new ThemeIcon('git-branch') },
+			{ id: 'tags', name: l10n.t('Tags'), icon: new ThemeIcon('tag') }
+		];
+	}
+	provideArtifactGroups(): SourceControlArtifactGroup[] {
+		return this._groups;
+	}
+
+	async provideArtifacts(group: string): Promise<SourceControlArtifact[]> {
+		const config = workspace.getConfiguration('git', Uri.file(this.repository.root));
+		const shortCommitLength = config.get<number>('commitShortHashLength', 7);
+
+		try {
+			if (group === 'branches') {
+				const refs = await this.repository
+					.getRefs({ pattern: 'refs/heads', includeCommitDetails: true });
+
+				return refs.map(r => ({
+					id: `refs/heads/${r.name}`,
+					name: r.name ?? r.commit ?? '',
+					description: `${r.commit?.substring(0, shortCommitLength)}`
+				}));
+			} else if (group === 'tags') {
+				const refs = await this.repository
+					.getRefs({ pattern: 'refs/tags', includeCommitDetails: true });
+
+				return refs.map(r => ({
+					id: `refs/tags/${r.name}`,
+					name: r.name ?? r.commit ?? '',
+					description: r.commitDetails?.message ?? r.commit?.substring(0, shortCommitLength)
+				}));
+			}
+		} catch (err) {
+			this.logger.error(`[GitArtifactProvider][provideArtifacts] Error while providing artifacts for group '${group}': `, err);
+			return [];
+		}
+
+		return [];
+	}
+
+	dispose(): void { }
+}