New FxPlug API FxParameterGroupingAPI_v1 for getting and setting Parameter Groupings

[belisoful]

Apple Feedback Assistant ID: MISSING!

Is your feature request related to a problem? Please describe.

When initializing the plugin and it's parameter structures, reconstructing subgroups is basically impossible without some wizardry.

Describe the solution you'd like

This is information that a FxPlug framework developer would love to have from FxPlug:

// This is the ID of the base SubGroup that all parameters are put into
#define FxPlugRootGroupID 0

@protocol FxParameterGroupingAPI_v1 <NSObject>
- (BOOL)isSubGroup:(FxParameterId) parameterID;   // <-iow, can it act as a Parent Parameter?
- (BOOL)hasSubParameters:(FxParameterId) parameterID;   // <-does parameterID have 1 or more subparameters.

- (UInt32)parameterSubCount:(FxParameterId) parameterID;  //. <- indexes similar to dynamic parameter API
- (FxParameterId) parameterIDAtSubIndex:(UInt32) index fromParameter:(FxParameterId) parameterID;

-(FxParameterId)getParameterSubGroup:(FxParameterId) parameterID; //the ID of the SubGroup containing parameterID
-(BOOL)setParameterSubGroup:(FxParameterId)subGroupID toParameter:(FxParameterId) parameterID;
@end

//This will move the parameter (paramID) from a SubGroup to the root level. 
// It would place the parameter next in line after it's prior subGroup, that's fine.
[groupingAPI setParameterSubGroup: 0 toParameter:paramID];

//Putting a new dynamic parameter into an existing subgroup after the fact would be useful
//  this would physically move the parameter into the subgroup, in motion or if the subgroup is published in FCP.
[groupingAPI setParameterSubGroup:subGroupID toParameter:paramID];

These methods should be immediately available after the SubGroup parameter and sub Parameter are created with FxParameterCreationAPI_v5 and within addParametersWithError.

This satisfies three use cases:

1. getting the sub parameters of a SubGroup (and count)
2. putting a dynamically created parameter into a group other than the Root Group for the plugin.
3. Getting the parent SubGroup parameter ID of a parameter.

This is to reconstruct the Group tree in an FxPlug framework.

Also, it would be very interesting if normal parameters could be a "group" container. So to make a Toggle also be able to act as a group for children parameters, and which would turn them all on or off. In this model, where any parameter can be a group, isGroup doesn't make sense and can be removed.

Describe alternatives you've considered
None.