Draft: Resolve "New `meltano state` command to rename, alter, print, and copy job states"

I'm still working through flake8 issues and need to finish documentation changes as well as a few scattered TODOs for docstrings/more informative errors/etc. and I'm writing up the API spec for being able to do these new CLI tasks via the API, but I was hoping to get some feedback on this first pass for a new meltano state command and associated StateService for managing Singer state. This ended up being a more significant change than I thought, but hopefully centralizing our scattered logic for Singer State into a single StateService will make these types of changes easier and/or more intuitive moving forward.

I'm particularly interested in getting feedback on my testing strategy and level of coverage and if there's potentially better approaches or existing patterns and/or fixtures that I could extend to better test these changes.

Closes New `meltano state` command to rename, alter, p... (#2754 - closed)