Git: Expose blame information in API

[TomasHubelbauer]

I'd like to request new method be added to the Git extension API detailed in:

https://github.com/Microsoft/vscode/blob/master/extensions/git/src/api/git.d.ts

My use case for this are is that in my extension MarkDown To-Do I currently shell out to Git to get blame for a line in order to determine the age of a MarkDown checkbox (- [ ] checkbox) on that line.

This feature request is prompted by @joaomoreno after his comment in #48674.

[joaomoreno]

Let's split this into two separate feature request issues. Can you clean this one up and create another one?

Let's keep the blame one here.

[anirudhrb]

The blame API is already available:

vscode/extensions/git/src/api/git.d.ts

Lines 175 to 177 in 8a80677

	blame(path: string): Promise<string>;
	log(options?: LogOptions): Promise<Commit[]>;
	}

and implemented like so:

vscode/extensions/git/src/git.ts

Lines 1485 to 1501 in 8a80677

	async blame(path: string): Promise<string> {
	try {
	const args = ['blame'];
	args.push(path);
	let result = await this.run(args);
	return result.stdout.trim();
	} catch (err) {
	if (/^fatal: no such path/.test(err.stderr || '')) {
	err.gitErrorCode = GitErrorCodes.NoPathFound;
	}
	throw err;
	}
	}

Is there something more that is needed?