[NEW] Add missing Services menu in application menu on macOS

[flphvlck]

@RocketChat/core

Closes #496

[gdelavald]

Thanks for doing this PR. We'll evaluate and get back to you if there are any changes needed.

[flphvlck]

Tested on macOS Sierra 10.12.6:

[gdelavald]

@phidlipus is the Services menu expected to be populated automatically?

[flphvlck]

@gdelavald Services menu will be populated only if you have configured some services. By default, if you haven't configured some services you will see only "Services Preferences".
The service menu should open, when you place your cursor on it.

[tomasgatial]

@gdelavald To my understanding, services menu is stateful, it should populate e.g. if you select a text within the application window. Then you can choose e.g. from text selection related services.

The does say it is a system standard menu. Why keep it disabled?

[gdelavald]

@phidlipus It's looking good! If I may add a suggestion, could you also add the services submenu to the context menu? I think that would improve the PR even further.
Right now the context menu is being modified in the SpellCheck.js file:

Rocket.Chat.Electron/src/public/lib/SpellCheck.js

Lines 183 to 217 in 26d9cca

	getMenu () {
	return [
	{
	label: 'Undo',
	role: 'undo'
	},
	{
	label: 'Redo',
	role: 'redo'
	},
	{
	type: 'separator'
	},
	{
	label: 'Cut',
	role: 'cut',
	accelerator: 'CommandOrControl+X',
	},
	{
	label: 'Copy',
	role: 'copy',
	accelerator: 'CommandOrControl+C',
	},
	{
	label: 'Paste',
	role: 'paste',
	accelerator: 'CommandOrControl+V',
	},
	{
	label: 'Select All',
	role: 'selectall',
	accelerator: 'CommandOrControl+A',
	}
	];
	}

I think it would be trivial to add the same submenu there.

[alexbrazier]

@gdelavald I might be wrong, but I don't think its common to have the services menu in the context menu

[gdelavald]

@alexbrazier I thought I saw some examples of it being useful. Haven't used osx long enough to be sure, I'll leave as is then, if someone feels like it could be useful we can discuss this in the future.

[flphvlck]

Thanks for merge.