Feature request: Standalone filter for a pair of file extensions

[andry81]

I want to compare comment lines of 2 files with different extensions. For example vbs <-> bat ignoring a comment line prefix.

Currently only the prediff filter works: https://github.com/WinMerge/winmerge/issues/2221

But a user have to add 2 regex filters and disable everything else:

Enabled	Ignore Case	Use RegExp	Find what	Replace with
☑	☐	☑	^'''	#
☑	☑	☑	^rem	#

But this applies for both, instead per extension if comparing both.