[TASK] Remove duplicated method in Rtehtmlarea\SelectImage

fileList() of Rtehtmlarea\SelectImage is almost an exact copy
of the parent implementation from ElementBrowser.

The patch removes fileList() from SelectImage and merges changes
to ElementBrowser.

It also fixes some bugs in magic image selector from RTE:
* Missing columns
* Wrong links to info page
* Fix "import selection" option

Resolves: #55765
Releases: 6.2
Change-Id: I78cb23de16b9516f953628aad10cf548f558bfd7
Reviewed-on: https://review.typo3.org/27414
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Marcin Sągol
Tested-by: Marcin Sągol
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters