Initial implementation of SolidQueue for running ActiveJobs

[mo-nathan]

To test:

1. Run the migrations.
2. Start bundle exec rake solid_queue:start in a new shell. 3 .Enter the Rails console in another shell.
3. In the console, run FieldSlipJob.perform_later(:test_arg).
4. cat tmp/fs-*.txt should show [:test_arg].

After you're done test you probably want to run rm tmp/fs-*.txt.

To actually get this working in production we'll need run the process in step 2 in the background. Also note that this does inflate the logs a bit since it polls the queue fairly often.

[coveralls]

coverage: 94.402% (+0.001%) from 94.401% when pulling b535a8ec900c281dc028c21ca93c7faa7e724fdc on njw-solid-queue into dfa9ac66dac2e48134d911e0b50aae281c73cdb0 on main.

[mo-nathan]

Thanks for the comments this draft PR. I've encorporated the changes into #2081. I'm going to close this PR.