Auto-connect and greedy plug behaviour for for icon-theme-breeze and gtk-theme-breeze snaps

store-requests
3

@review-team: has anyone had a chance to look at this? Getting this sorted would help in getting the new gtk-common-themes snap release promoted to stable (since it drops the Breeze themes).

The desired snap declaration would be similar to what was granted for the MATE theme snaps. Namely:

  1. for gtk-theme-breeze:
    slots:
  content:
    allow-auto-connection:
      -
        plug-attributes:
          content: $SLOT(content)
        slot-attributes:
          content: gtk-3-themes
        slots-per-plug: *
      -
        plug-attributes:
          content: $SLOT(content)
        slot-attributes:
          content: gtk-2-themes
        slots-per-plug: *
  2. for icon-theme-breeze:
    slots:
  content:
    allow-auto-connection:
      -
        plug-attributes:
          content: $SLOT(content)
        slot-attributes:
          content: icon-themes
        slots-per-plug: *

The aim being to allow application snaps requiring theme data to connect to these snaps in parallel with the gtk-common-themes snap.