docs: add/remove elements for more clarity on the version of the docs you're on

[agilgur5]

Motivation

In CNCF Tech Docs Office Hours on Sept 25th, a couple of items in the docs stood out as confusing or lacking clarity around versions, including the GH link and a lack of version in the header/logo/home button

• which I briefly summarized in the Oct 1st Contributor Meeting
• technically a follow-up to #11390

Modifications

• remove version number from GH link

  • use JS here as this is not overrideable via partial:
  • the source partial uses a JS component
  • follows JS customization docs

• add minor version number underneath the logo in the header (the "home" button)

  • when no version or latest, use "dev" instead, as that is more clear than "latest", per Tech Docs OH
  • unfortunately can't change the actual name in RTD though
  • this uses some hacky JS to insert the version based on the URL since there is no other way to configure this in mkdocs
  • versioning is outside of its scope, either via plugins, or in our case, RTD, so can't be done via partial either
  • organize the JS a bit more into functions at least though

• handle sidenav vs. header on mobile

Verification

Visually inspected. See screenshots:

Before:

Header:  SideNav: 

After:

Header:  SideNav: 

Future Work

1. [ ] Also add a floating version warning banner for old versions and latest, as mentioned in the TechDocs Office Hours (referencing https://github.com/etcd-io/website/issues/813) as well as my own comments in https://github.com/argoproj/argo-workflows/issues/11390#issuecomment-2007818981 (referencing CD's banner)
   • the RTD version warning gets ignored and closed too easily. It's also permanently closed right now per https://github.com/readthedocs/addons/issues/133#issuecomment-2192770978 / https://github.com/readthedocs/addons/pull/283