Add testing and packaging files

[ktactac-ornl]

Short description of the changes:

Migrates gitlab CI to github

Long description of the changes:

• create GH CI files
• delete GL CI files
• move issue/PR templates
• update an annoying version test without affecting its purpose

Check list for the pull request

• I have read the [CONTRIBUTING]
• I have read the [CODE_OF_CONDUCT]
• I have added tests for my changes
• I have updated the documentation accordingly

Check list for the reviewer

• I have read the [CONTRIBUTING]
• I have verified the proposed changes
• best software practices
  • all internal functions have an underbar, as is python standard
  • clearly named variables (better to be verbose in variable names)
  • code comments explaining the intent of code blocks
• All the tests are passing
• The documentation is up to date
• code comments added when explaining intent

Manual test for the reviewer

References

8190: [DRTSANS] Migrating the source to GitHub

[glass-ships]

not by any means necessary, but this could be a good opportunity to test out packaging via pixi - there's a setup-pixi github action we can use.

but also i could just play around with that in a separate PR.

[glass-ships]

you may have figured it out already but test_simple is failing because versioningit is set to get the latest version from our tags, but github doesn't have any tags yet - those are still in gitlab

i straight up lied, we definitely have the tags in gh too. not sure why my pipeline is failing to grab the right version...

[glass-ships]

looks good!

only other question i have is, i see we do git submodule update --init but i don't see any steps for git lfs, so we're skipping a lot of tests.

is that something you're still working on?