[FEATURE] Add SplFileInfo implementation to get file mimeType

\TYPO3\CMS\Core\Type\File\FileInfo provides a new method
getMimeType() to get the MIME type of a file, e.g. text/html.

Custom implementations to determine the MIME type can be added
with the hook:

$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS'][\TYPO3\CMS\Core\Type\File\FileInfo::class]['mimeTypeGuessers']

The FAL LocalDriver also uses this new API.

Resolves: #60019
References: #46777
Releases: master
Change-Id: Ia2fa95d2ef6452f8022e33f1b1d2a9336f3e0303
Reviewed-on: http://review.typo3.org/31256


Reviewed-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Tested-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Reviewed-by: Frans Saris <franssaris@gmail.com>
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Steffen Müller <typo3@t3node.com>
Reviewed-by: Steffen Müller <typo3@t3node.com>