Sorting by Insertion Date actually sorts by modification date

Description

Sorting by Insertion date actually sorts by modification date.

SORT_INSERTIONDATE is almost never used, SORT_LASTMODIFICATIONDATE is always used.

UI Strings related to sorting should be improved to correctly indicate last modification date, and sort by insertion date should be implemented.

Correclty implementing insertion date sort should also expose the medialibrary insertion date value, so that it could be displayed (specifically in the headers for the app's browsers)

This is what causes to #2920 (closed)