Theme Showcase: Add Atomic support for auto-loading homepage modal

[sixhours]

Proposed Changes

• Following up on Andy's work, add the siteId param to themeHasAutoLoadingHomepage selector so we can check themes for the auto-loading-homepage tag whether on wpcom or individual Atomic sites
• Remove checks for isJetpackSite/isAtomicSite when using the auto-loading-homepage action since we no longer want to exclude them.
• Requires upcoming Jetpack changes that should be available to Atomic sites Wed. Jun 19 in Minor: Add action before switch theme jetpack#24818
• This shouldn't be deployed until after we have the functionality ready in wpcomsh.

Testing Instructions

• Switch to this PR, navigate to /themes on your Atomic site.
• Clicking on a theme should pop up the auto-loading home page modal (if the theme supports it -- some themes to try are Appleton, Dorna, Winkel):

• Older themes (like Dara or Hexa) should not display the modal; they should instead just activate.
• The actual homepage switch won't work until we use the new hook introduced in Minor: Add action before switch theme jetpack#24818 from within wpcomsh, which will require a separate diff.

Related to 997-gh-Automattic/wpcomsh and Automattic/jetpack#24818 to fix #56869

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-37988

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-37988&env=jetpack

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

Sections (~48 bytes removed 📉 [gzipped])

name      parsed_size           gzip_size
themes         -225 B  (-0.0%)      -18 B  (-0.0%)
theme          -225 B  (-0.0%)      -30 B  (-0.0%)
checkout        +75 B  (+0.0%)      +39 B  (+0.0%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[sixhours]

This isn't quite working as expected:

• Even if the theme has the auto-loading-homepage tag, it's not available to the siteId via getTheme unless the site has activated the theme at least once, thereby adding it to its individual library.
• Once the theme has been activated on the site, and if it has the auto-loading-homepage tag, the modal will work as expected.

So I think we need to fall back to checking against wpcom if the theme is not yet available under the Atomic siteId.

[andres-blanco]

I've set up a new AT site and it works as expected! I will start working on the wpcomsh change 💪

[andres-blanco]

An extra change to Jetpack needed to be issued to allow the dont_change_homepage argument in the /sites/%s/themes/mine endpoint. This is the PR.

[andres-blanco]

@sixhours Do you think this should be enabled on Jetpack or only on Atomic? My initial guess was that this should only be enabled on Atomic.

[sixhours]

Do you think this should be enabled on Jetpack or only on Atomic? My initial guess was that this should only be enabled on Atomic.

Yep, only Atomic for now, I would think. Headstart annotations have not been widely used (if at all) for non-Atomic Jetpack sites.

[andres-blanco]

Closing this since the work done by this PR was split in this other 2:

• add siteId as param to themeHasAutoLoadingHomepage #65943
• Homepage replacement on Atomic: Toggle modal based on flag #65976