A number of tweaks for Convolution effect (#8226)

- Some parameter renames
- Remove some unnecessary val_min/max/default duplications which were unnecessary since set_type() did them
- Added coupled deactivation for tilt filter parameters
- Added Dry and Send init FX presets
- Moved Convolution to Time & Space category
- Adjusted the range of Start, Reverse From and Tilt Slope parameters
- Small adjustment in layout of sliders and the IR selector menu
- Adjusted the names of folders for factory, 3rd party and user impulse responses (impulses_factory, impulses_3rdparty, Impulses)
- Added some factory and 3rd party food for the convolver!

Author: mkruselj