Provide CLI utilities in Langium

[msujew]

To improve development speed for CLIs build on Langium, we need to provide utilities for different CLI specific issues:

• Initializing workspaces based on file paths
• Interacting with the shell in different ways (colors, reading input, etc.)
• Watch ability which correctly updates documents based on file system events

[spoenemann]

Note: We should avoid adding dependencies to the base package for these utilities. Would it be an option to offer some utilities in langium-cli so it can be used as a library?

[spoenemann]

Duplicate of #174?

[spoenemann]

I tend to regard this as out of scope for Langium now. Shall we close this?

[montymxb]

I would agree for the 2nd & 3rd points at the least. We can always open up a more relevant issue should this come up, and target on that specific case. I'll close this out preemptively, we can always discuss this later (or in a dev meeting).