Ability to extend supported extension - file parser mapping

[fractal3000]

It is a more profound fix of the problem #3660

Steps To Reproduce

Create project with search add-on.
Create entity with field of "FileReference" type.
Create search index definition with pointing of the attribute.
Start project
Login to UI
Add enitities data with adding files of some not-document format(e.g. sql)
See the console log

Current Behavior
Long stack trace is appeared.

Expected Behavior
There is human readable message obout using not supporting file format.

Steps To Reproduce

Create project with search add-on.
Create entity with field of "FileReference" type.
Create search index definition with pointing of the attribute.
Start project
Login to UI
Add enitities data with adding files without any extension
See the console log

Current Behavior
Long stack trace is appeared.

Expected Behavior
There is human readable message obout using not supporting file format.

The problem with uppercase extensions also should be solved #3696

A programmer should be able to add more supported file extensions without modifing any service beans logic.