BLD: split ui dependencies into subpackage

[tangkong]

Description

Splits happi gui dependencies into subpackages (pip) or separate outputs (conda)

Motivation and Context

closes #347
closes #340

How Has This Been Tested?

Added some ui tests, but mostly relying on CI here to assess failure

Where Has This Been Documented?

This PR

Pre-merge checklist

• Code works interactively
• Code contains descriptive docstrings, including context and API
• New/changed functions and methods are covered in the test suite where possible
• Test suite passes locally
• Test suite passes on GitHub Actions
• Ran docs/pre-release-notes.sh and created a pre-release documentation page
• Pre-release docs include context, functional descriptions, and contributors as appropriate

[tangkong]

In the lightpath, we only adjusted the pip builds in the repo, and left the conda outputs for the feedstock. I'm going to verify that the pip builds work here, then try applying the same conda output recipe format to the conda recipe here. I think it'd be nice to have a build check independent of conda-forge, but I'm not sure if any of the output setup is conda-forge specific

Edit: conda multi-output builds were not happy

[tangkong]

A note: CI should remain unchanged as long as the .[test] dependency set remains unchanged.

[ZLLentz]

There's at least some potential consideration for not having PyQt5 here, I don't remember best practices for qtpy apps

[tangkong]

We include PyQt5 for both atef and lightpath, which I was looking at for reference. You're right that qtpy is supposed to be our qt-agnostic translation layer, though without it pip won't install PyQt5. (at least from what I can verify from my testing)

[ZLLentz]

I think this split is pretty reasonable 👍

[ZLLentz]

Looks reasonable
Missing release notes