FR: APVTS - removeParameterListener() for all params

I’m finding myself rarely wanting to remove just a single parameter from a listener when calling removeParameterListener, which is especially true when killing off an editor or some custom components.

I’d prefer something like this:

// In "juce_AudioProcessorValueTreeState.cpp":
void AudioProcessorValueTreeState::removeParameterListener (Listener* listener)
    for (auto& iter : adapterTable)
        iter.second->removeListener (listener);

// In "juce_AudioProcessorValueTreeState.h"
    /** Removes all parameter callbacks registered with the listener. */
    void removeParameterListener (Listener* listener);

// In my own code, say a destructor of a component:
apvts.removeParameterListener (this); // Don't care about params anymore, and don't care to track 'em here.