Use wp_star_rating() on Add Themes screen

[SergeyBiryukov]

Background: #26814

Unlike Add Plugins screen, the Add Themes screen does not use wp_star_rating() and tries to recreate similar markup with JS.

The markup, however, is a bit different, and has a few issues:

• Does not work for RTL (see the before/after screenshots).
• Requires a lot of custom CSS styling.
• Uses different classes and is visually inconsistent with plugin ratings.
• Does not appear to be accessible.

We should add an echo argument to wp_star_rating() (like we did for wp_terms_checklist() in [33904]) and use the existing function instead.

There is a slight visual change (the "based on %s ratings" string becomes redundant, because wp_star_rating() has a similar text as a title attribute and screen reader text).

[SergeyBiryukov]

Related: ​#meta1266

[SergeyBiryukov]

In 35005:

Add echo parameter for wp_star_rating().

See #34080.

[SergeyBiryukov]

In 35006:

Use wp_star_rating() on Add Themes screen:

• It works correctly for RTL
• Requires less CSS styling
• Is visually consistent with plugin ratings
• Is more accessible

Fixes #34080.