Queues: convert to Python library

[polybeandip]

Closes #2186 and the test harness part of #2191.

More specifically, this PR does the following:

• set up separate directories for our package, data file generation, and tests
• move each queue's python generator and associated main component to different files: main components are in test/
• remove PCQs from data_gen/gen_queue_data_expect.sh (for now)
• tweak runt stanzas to work with new file structure
• tweak github actions to install queues for CI and run gen_queue_data_expect.sh
• gitignore large .data and .expect files
• fill in README for our library
• update links in the docs to our new file locations and add install instructions

[polybeandip]

@anshumanmohan is it okay for me to move sdn.py (and it's associated data and expect file)?

I think I remember you saying these files were artifacts for a different project. For this reason, I wanted to check if it's okay for me to move them around and tweak their associated runt stanza (not the cmd part, only path).

[anshumanmohan]

Yay, thank you! Been looking forward to these changes haha. I will ask @csziklai and @KabirSamsi to glance over this PR and offer their own reviews if they’d like. It’s a great way to stay in the loop. Regardless, I’ll go through and review it tomorrow EoD

[anshumanmohan]

Yes, that’s okay re: SDN! I’d like to resuscitate it and have it hang around somewhere, so just let me know where it ends up

[polybeandip]

You can find it at frontends/queues/tests/sdn_test.py.

I've made sure to alter the SDN runt stanzas so they point to this new location now. Those tests still pass just fine!

[EclecticGriffin]

wowowowow, this might be a record for deleted lines!

[anshumanmohan]

Wowowow thanks for this massive massive cleanup! 👏 It's really looking a lot more organized and maintainable. I have reviewed this and learned a bunch from the process. Merge at will!