Update custom menu styles (#149187)

* Initial updates

* Add border radius

* Address PR feedback

* Fix typo

* Update shadow blur

* Update LR padding and use description foreground for shortcuts

* Typo

* Fix separator padding/margin

* fix jumpy items in hc themes

* Fix shadow and border radius

* Use opacity for keybinding for better color blend

* Update min width and container padding T/B

* Revert actionbar margin and remove unnecessary menu css file

* Ensure menus respect 0 horizontal margin rule

* set bg/fg color on menu container

* better fix for jumpy menu items

* use outline instead of border

* clean up dead css in style.css
fix opacity for separators in menus

* bring back vertical action bar margins

* Remove old CSS import

Co-authored-by: SteVen Batten <sbatten@microsoft.com>

extensions/theme-defaults/themes/dark_vs.json

@@ -12,7 +12,7 @@
 		"activityBarBadge.background": "#007ACC",
 		"sideBarTitle.foreground": "#BBBBBB",
 		"input.placeholderForeground": "#A6A6A6",
-		"menu.background": "#252526",
+		"menu.background": "#303031",
 		"menu.foreground": "#CCCCCC",
 		"statusBarItem.remoteForeground": "#FFF",
 		"statusBarItem.remoteBackground": "#16825D",