Use bslib's new nav() api to implement tabPanel() and friends (#3388)

* Use bslib's new nav() api to implement tabPanel() and friends

* bslib won't be re-exporting prepend/append tab since they've been superceded by insertTab()

* Update DESCRIPTION

* Use the new bslib::page_navbar()

* Leverage bslib::page_navbar()'s more intelligent title->windowTitle handling

Closes #2310

* fix name change

* Make sure navbarPage() isn't browsable by default

Author: cpsievert

DESCRIPTION

@@ -91,7 +91,7 @@ Imports:
     withr,
     commonmark (>= 1.7),
     glue (>= 1.3.2),
-    bslib (>= 0.2.4.9003),
+    bslib (>= 0.2.5.9001),
     cachem,
     ellipsis,
     lifecycle (>= 0.2.0)