Fires at the top of each of the tabs on the Install Themes page.

The dynamic portion of the hook name, $tab, refers to the current
theme installation tab.

Possible hook names include:

• install_themes_block-themes
• install_themes_dashboard
• install_themes_featured
• install_themes_new
• install_themes_search
• install_themes_updated
• install_themes_upload

do_action( "install_themes_{$tab}", $paged );