[BUGFIX] Allow longer file-endings in typoscript directory includes

Directory includes now allow more liberal substrings to include files
not only based on their extension (*.typoscript) but based on the last
part of their filename (*.setup.typoscript).

Resolves: #82543
Releases: master, 8.7
Change-Id: Ic2111b98a6e3935b542addfd712f4256aa40f888
Reviewed-on: https://review.typo3.org/54443


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benjamin Kott <benjamin.kott@outlook.com>
Tested-by: Benjamin Kott <benjamin.kott@outlook.com>