Remove kissfft

[fuzzard]

Description

Remove kissfft and its usage

Motivation and context

@neo1973 pointed out in #23808 that this doesnt seem to be used. So nuke it i guess.
Alternative to cleaning up and removing the lib from tree in #23808.

@notspiff pointed me to 2a953d5 where its usage was removed. so dead code it is.

How has this been tested?

What is the effect on users?

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• Student submission (PR was done for educational purposes and will be treated as such)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[garbear]

With surgical precision, 1K lines removed, 1 added. I'm actually disappointed about the 1.