Theme Tiers: Warn user when switching away from a theme they'll lose access to

[dsas]

What

Ensure users understand when they're moving away from a theme that they'll then lose access to, due to the themes tier being changed.

Why

We want to re-tier some themes (p7DVsv-m5X-p2). Users on a plan that is a lower tier to the theme can continue using the theme, but if they switch away from it, then they will lose access to the theme.

To manage their expectations and moderate HE workload we want to display a message ensuring that users understand this. It should only be displayed when it's actually a problem. i.e. if the user is on a lower-tier plan than the themes current tier. A small number of edge cases aside, this will mostly only affect users on the free and personal plans.

How

We can update the theme activation modal, along these lines (h/t @inaikem):

We should redraft the text and get the input of copywriters if necessary.

We should also add some tracks events:

• We want to find out who sees the modal and decides against changing themes
• We want to find out who sees the modal and does change themes
• We also want to be aware of how many people create support requests.

[github-actions]

OpenAI suggested the following labels for this issue:

• [Feature Group] Appearance & Themes: The issue addresses features related to user interaction with themes, specifically regarding tier access.
• [Feature] Appearance & Themes: The content is focused on managing user access to themes based on their subscription tier.
• [Feature] Plans & Upgrades: The issue discusses implications of theme access that relate directly to the user's subscription plan and tier information.

[mmtr]

Updated the issue to include the tracking requirements that we discussed in the meeting.

• We should add some tracks events
  • We want to find out who sees the modal and decides against changing themes
  • We want to find out who sees the modal and does change themes
  • We also want to be aware of how many people create support requests.

[rcrdortiz]

These changes are now live.