Added CLI to sanitize those file entries that hold a broken/corrupt MIME type information

New CLI is named sanitizefilemimetypes and accepts two inputs: The identifier of the context whose files to sanitize (mandatory) and an optional comma-separated list if MIME types that should be considered as corrupt.

Usage:
sanitizefilemimetypes
-c,--context <arg> Required. The context identifier
-h,--help Prints a help text
-i,--invalids <arg> An optional comma-separated list of those MIME
types that should be considered as broken/corrupt.
Default is application/force-download,