Type hinting developer docs

[ksunden]

PR summary

• Update devdocs with more details about type hinting, especially deprecations
• Bring existing parameter keyword only deprecations in line with documentation
  • Deprecated and slated for removal deprecations are not added, though going forward we suggest not removing the hints where they already exist until expiry.

I considered adding something regarding the behavior of the alias decorator (namely that the aliases are not type hinted, added to the mypy-stubtest-allowlist.txt file)
But there was not already a section about that decorator, and it is rare enough that it gets added that I don't necessarily think its warrented to write one just for this.

PR checklist

• [N/A] "closes #0000" is in the body of the PR description to link the related issue
• new and changed code is tested
• [N/A] Plotting related features are demonstrated in an example
• [N/A] New Features and API Changes are noted with a directive and release note
• Documentation complies with general and docstring guidelines