[BUGFIX] Make ImageService Exception more descriptive

The Extbase FAL ImageService throws an exception if the src
parameter is not resolved to a proper File/FileReference object.

The patch adds the $src parameter to the Exception message
in order to detect in an easier way where something went
wrong.

Resolves: #66106
Releases: master, 7.6
Change-Id: Ia4aa5f9fe5c5c98005e94dd563afbd6e44457056
Reviewed-on: https://review.typo3.org/47494


Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>