[FEATURE] Combined Dry/Wet Gain Control

[jatinchowdhury18]

Is your feature request related to a problem? Please describe.
Currently there is no easy way to change the global output level of the plugin.

Describe the solution you'd like
There should be a way to "link" the global Dry and Wet level parameters so that changing one value changes both of them together, perhaps using SHIFT or some other modifier key.

Additional context
We may want to make the "fine-adjustment" level 0.05 instead of 0.1 when the sliders are linked just to make sure the user has enough precision in fine-tuning the output level.