Fires before each of the tabs are rendered 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_pre_block-themes
• install_themes_pre_dashboard
• install_themes_pre_featured
• install_themes_pre_new
• install_themes_pre_search
• install_themes_pre_updated
• install_themes_pre_upload

do_action( "install_themes_pre_{$tab}" );