Lay the groundwork for migrating Airflow CLI to Rich+Click

[blag]

This is the first PR of what will be a series of PRs breaking up #22613 into smaller, more reviewable chunks. The end result will be rewriting the existing airflow CLI to use Click instead of argparse. For motivation, please see #22708.

This PR installs Click, adds constraints to Rich_Click so we can rely on some nice features in recent versions of that, adds a new barebones airflow-ng console script, and tweaks some CLI internals to be more flexible between argparse and Click.

To see how this initial groundwork will be used by future PRs, see #22613, and to see how some of this will be used please see #24591.

[uranusjr]

Since this import is used only locally in this file, I’d prefer it use rich_click.

Suggested change

	import rich_click as click
	import rich_click

[blag]

That looks like a reasonable suggestion, but that import comes straight out of the rich_click documentation:

Usage

Import as click

To use rich-click, switch out your normal click import with rich-click, using the same namespace:

import rich_click as click

That's it ✨ Then continue to use click as you would normally.

The rich_click package tries to be a superset of Click. When people are trying to add additional options or commands, I am trying to direct them to the Click documentation, since that is what's relevant to them.

If that justification doesn't sway you, I'm happy to change it if you insist (just confirm in a comment below).

[blag]

This got merged before I had a chance to change this.

[potiuk]

One small thing (for next PR). Rich-click 1.5 introduced some changes that might cause incompatibilities. I tihnk bumping up to > 1.5 is a good idea.

[Bowrna]

@blag It's slightly disheartening to see the Click CLI for airflow getting closed after working on it for a few commands. If there is any plan to do the groundwork or research work for checking the best way to set CLI commands for airflow, could you include me too? I am glad to extend my help and give my contribution to that part. Especially with trying something like using mypyc to speed up the code execution, i can help in some research work in that area.

[blag]

@Bowrna Absolutely, I'll keep you in mind if/when I decide to try refactoring the CLI again. Thank you again for all of your work!