Fix monaco localization

[msujew]

What it does

Closes #13438
Closes #13556

Moves the monaco localization code into the monaco-init.ts file so that the localization function is overriden before any other monaco code is loaded.

Fixes the automatic install of language packs as a drive-by.

How to test

1. Change the language of Theia to any other than English.
2. Open the context menu of a monaco editor. It should be correctly translated

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[msujew]

@tsmaeder ping, it's a small change :)

[tsmaeder]

¡Me gusta!