Themes: Don't navigate away from themes.php on author click in grid view

[kovshenin]

Authors are hidden by default, but when you start a search, if your search matches part of an author name, the author names will be revealed in the grid view, along with the author URI links. So when you click on a theme, if you're unlucky enough to hit the author area, you'll be navigated away from themes.php.

1. Appearance - Themes
2. Search for "wordpress" to reveal the author on the twenties
3. Click the author name
4. The modal will be shown, but you'll be taken to wordpress.org soon after

[kovshenin]

In 26433.diff​: prevent any additional actions that are not in .theme-actions before expanding.

[matveb]

Related to #26425.

[nacin]

In 26684:

Theme: When showing an author in the grid (during a search), don't include the author's link.

fixes #26433.