Moving some template links to Python

[choldgraf]

We currently link two theme-specific things in a Jinja extrahead block:

• Our favicon links (e.g. for apple icons)
• Our Google Analytics code

However, some themes over-write the extrahead block, and if they don't realize that this functionality needs to be explicitly included, then it will fail silently. For example:

• Docs are missing GA code bokeh/bokeh#12133

So this PR switches this to use Sphinx for linking these files, instead of a custom Jinja template. This should make this behavior less brittle.

cc @bryevdv

[bryevdv]

@choldgraf FWIW with the newer favicon support in the theme, we realized we can stop overriding extrahead altogether. However I do think this is a good change, and that having a safe user-addressable block for anything extra that might need injecting is a good feature.

[jarrodmillman]

This LGTM. @choldgraf Any reason to wait on merging this?

[choldgraf]

I'm +1 on merging if nobody finds something wrong with it!

[jarrodmillman]

Maybe we could merge this, release pydata-sphinx-theme 0.9rc1, and then ask folks to test it. We can wait to finalize 0.9 until we have feedback from folks using google analytics. If that seems reasonable, I propose we:

1. merge this
2. rename master to main
3. release 0.9rc1
4. ask folks to test it
5. assuming we find no issues, release 0.9
6. if we run into issues, quickly release 0.9.1

[choldgraf]

That sounds great to me 🙂