basic repo maintenance - Githubissues

I added a Makefile target to generate Python classes for all our meta-model YAML files (instead of only running gen-project which does meta.yaml with -mergeimports=False).
I also noticed the codespell config was ignoring all the yaml files with the regex it used to stop spell-checking on generated .HTML files. I removed that regex and limited it by file extension instead. I added a makefile target to run codespell locally and cleaned up the reported errors.
I added a very basic yaml linter to the GH actions and a Makefile target to run it. The next step is using our own linkml-lint to do the equivalent level of linting for these older schemas that might take awhile to move to the new standards (e.g. Biolink, linkml-model, etc.).
- while in the GH actions, I also added a bit of code to re-run the tests on modification of a PR.
I made codespell, yamllint dev dependencies in pyproject.toml. I know there is more to do in the pyproject.toml file - I stopped short of doing the rest!
It's unclear to me why we need setup.py and setup.cfg any longer. These are also removed in this PR.
finally, I added linkml:notes to all our Types classes to indicate on our generated doc, that we should use lowercase names for these instead of uppercase.

linkml / linkml-model