Add LDAP group membership management to the Directory modal, pin Groups sort bar, merge Directory columns

- Directory modal's Associated LDAP Groups tab now lets you view/add/remove
  members and owners of each associated group directly, reusing the same
  PUT/DELETE group/:group/:uid routes and member-mapping pattern already
  used on the Groups page -- no backend change needed.
- Groups page: the search/sort bar is now sticky, staying visible while
  scrolling through a long group list. Introduces --sw-content-offset (set
  in top.ejs alongside #spa-shell's margin-top) so an in-page sticky
  element can offset itself below the fixed navbar/update-banner instead
  of being hidden behind them at the viewport's true top:0.
- Directory table: Kind/Name/Env/Host merged into a single "Resource"
  column, matching the same information more compactly.
- app-base.js (byte-identical across the 3 apps): added app.util.revealItem(),
  which scrolls a just-added/-edited element into view and flashes its
  background -- wired into the Directory table, the Groups tab's member
  list, and the Groups page's create-group flow.
- Bumped @simpleworkjs/frontend to ^0.2.7 (published with the same
  revealItem() addition for any future consumer of its app.js, even though
  none of the 3 apps currently load that file directly -- they use the
  legacy app-base.js instead).

nodejs/public/css/styles.css

@@ -7,6 +7,12 @@ body {
 	display: flex;
 	flex-direction: column;
 	min-height: 100vh;
+	/* Height of the fixed navbar (plus the update banner, while shown --
+	   see top.ejs's showUpdateBanner/dismissUpdateBanner). Lets an in-page
+	   sticky element offset itself below both fixed elements via
+	   `top: var(--sw-content-offset)` instead of colliding with them at the
+	   viewport's true top:0. */
+	--sw-content-offset: 4.5rem;
 }
 
 #spa-shell {