Add option for always visible action buttons in side panels.

[JacksonKearl]

Fixes #37714 by adding a settings config option to keep side menu title bar action buttons visible whenever their panel is expanded.

[msftclas]

All CLA requirements met.

[JacksonKearl]

Touches many files because I needed to inject an IConfigurationService into ViewletPanel. Not sure if there is a way to do this other than passing the service up from all subclasses and letting the base instantiationService.createInstance() handle instantiating the config service.

[JacksonKearl]

I am not sure why these changes would cause this test:

test('getUntitledWorkspaceSync', done => {
	let untitled = service.getUntitledWorkspacesSync();
	assert.equal(0, untitled.length);

	return createWorkspace([process.cwd(), os.tmpdir()]).then(untitledOne => {
		untitled = service.getUntitledWorkspacesSync();

		assert.equal(1, untitled.length);
		assert.equal(untitledOne.id, untitled[0].id);

		return createWorkspace([os.tmpdir(), process.cwd()]).then(untitledTwo => {
			untitled = service.getUntitledWorkspacesSync();

			assert.equal(2, untitled.length); // here

			service.deleteUntitledWorkspaceSync(untitledOne);
			untitled = service.getUntitledWorkspacesSync();
			assert.equal(1, untitled.length);

			service.deleteUntitledWorkspaceSync(untitledTwo);
			untitled = service.getUntitledWorkspacesSync();
			assert.equal(0, untitled.length);

			done();
		});
	});
});

to fail with untitled.length being 1 instead of 2 at the marked location, on AppVeyor. Could someone with more knowledge of the ecosystem possibly take a look? Locally (macOS) the tests all pass except

FileSearchEngine Files: *.* exclude with unicode:
     Error: timeout of 5000ms exceeded. Ensure the done() callback is being called in this test.

which also fails for me on master.

[JacksonKearl]

Added some comments and now it works. Is the build server known to be a bit temperamental?

[joaomoreno]

@JacksonKearl Great job. Yeah, unfortunately there's no way to get around touching all those subclasses. I took care of the merge conflicts and did minor refactoring in the PanelViewlet. Thanks! 🍻

[joaomoreno]

Renamed setting to workbench.view.alwaysShowHeaderActions. #44044