[BUGFIX] Limit amount of data fetched by the page tree

Page tree will fetch just 2 levels of pages plus pages which
are expanded on the initial load.
Next levels are fetched on demand via Ajax when expanding the node.
Search work server side now (hit enter). To clear search, click on "x"
button.
If you select a page when filtering, it's kept selected after
removing the filter.

Releases: master, 10.4, 9.5
Resolves: #88943
Resolves: #88098
Resolves: #88259
Change-Id: Ie83839ce801c509f24c1e2c1dc516bce9599d55e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62086


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Sybille Peters <sypets@gmx.de>
Tested-by: Dennis Prinse <dennis@dennisprinse.com>
Tested-by: Marcus Schwemer <ms@schwemer.de>
Tested-by: Uwe Trotzek <trotzek@citeq.de>
Tested-by: Richard Haeser <richard@maxserv.com>
Reviewed-by: Marcus Schwemer <ms@schwemer.de>
Reviewed-by: Richard Haeser <richard@maxserv.com>