fix(ui): misc ui fixes (#39336)

1. Give menu items an inset pill highlight, text position and menu width are unchanged in most menus
1. Add arrow key, Enter, Space and Escape handling to all tippy menus
1. Mark the keyboard cursor of fomantic and tippy menus with the focus ring instead of the hover background
1. Mark the current dropdown item with the active color so it stands out from the hovered one
1. Stop navbar dropdown links from taking the navbar item hover color
1. Replace the actions job log options dropdown with the shared tippy menu, its hover highlight was invisible
1. Stop changing font weight on active and selected menu items, it resized rows while arrowing
1. Stretch the "All extensions" button in the diff file extension filter to the full menu width
1. Fix the actions run summary block covering the panel's rounded corners and indenting wrapped stats

web_src/css/modules/navbar.css

@@ -34,8 +34,7 @@
   background: var(--color-active);
 }
 
-#navbar a.item:hover,
-#navbar button.item:hover {
+#navbar :is(a, button).item:not(.dropdown *):hover {
   background: var(--color-nav-hover-bg);
 }