#7793677 Themes Showcase: Replace empty search card with more theme options

Fixes Automattic/dotcom-forge#1453

Proposed Changes

Replaces the previous upsell nudge displayed on empty searches, with a new card that offer users to perform the following actions:

• Design your own theme / homepage: Allow users to change their own homepage in the site editor (only in the logged-in showcase, and only if the site has a block theme active).
• Do it for me: Upsells the DIFM service.
• Upload a theme: Upsells the Business plan and/or nudges users to upload a third-party/custom theme missing.

Screenshots

Conditions	Before	After
Showcase: Logged-in Plan: Free Current theme: Block theme
Showcase: Logged-in Plan: Business Current theme: Block theme
Showcase: Logged-in Plan: Business Current theme: Legacy theme
Showcase: Logged-out

Events

The following events a tracked when a user clicks on any of the options:

• Design your own theme / homepage:
  • Event: calypso_themeshowcase_more_options_design_homepage_click
  • Props:
    • site_plan: The site plan.
    • search_term: The term searched.
    • destination: Where we are sending the user to. The only possible value right now is ‘site-editor’, but it can be extended in the future once we can start the Pattern Assembler.
• Do it for me:
  • Event: calypso_themeshowcase_more_options_difm_click
  • Props:
    • site_plan: The site plan.
    • search_term: The term searched.
• Upload a theme:
  • Event: calypso_themeshowcase_more_options_upload_theme_click
  • Props:
    • site_plan: The site plan.
    • search_term: The term searched.
    • destination: Where we are sending the user to. Possible values are signup (for the logged-out showcase), upload-theme if the site has an eligible plan, or checkout if the site doesn’t have an eligible plan.

Testing Instructions

• Use the Calypso live link below
• Switch to a Free site with a block theme active
• Go to Appearance > Themes
• Enter a term that doesn’t produce any result
• Observe the new card
• Make sure it includes 3 options: Design your own homepage, Do it for me, Upload theme
• Make sure it looks good and the copy is clear
• Make sure all actions redirect to the appropriate place
• Make sure it is responsive on mobile viewports
• Switch to a Simple site with a Business plan and a block theme active
• Make sure the “Upload theme” action no longer upsells the Business plan
• Make sure the “Upload theme” action sends users to /theme/upload/:site
• Activate a legacy theme
• Make sure the “Design your own homepage” action is no longer visible
• Make sure the “Upload theme” action sends users to /wp-admin/theme-install.php
• Switch to an Atomic site with a Business plan
• Open the /themes path on an incognito window
• Enter a term that doesn’t produce any result
• Make sure it includes 2 options: Do it for me, Upload theme
• Make sure the “Upload theme” action initiates the Business plan signup flow