support dynamic parameter changes in parameters extension

[atsushieno]

It is similar to #44, but while the issue was about ports it is about parameters this time.

It would be done by adding on_parameter_list_changed(AndroidAudioPluginHost* host, AndroidAudioPlugin* plugin) in parameters host extension, like:

typedef void (*parameters_extension_on_parameter_list_changed_func_t) (AndroidAudioPluginHost* host, AndroidAudioPlugin* plugin);

typedef struct aap_host_parameters_extension_t {
    parameters_extension_on_parameter_list_changed_func_t on_parameters_changed;
    parameters_extension_get_mapping_policy_func_t get_mapping_policy;
};

... assuming that the host can retrieve these properties from AndroidAudioPlugin*:

• pluginId
• instanceId

Especially for instanceId, we currently do not provide it by any way so we will have to add extra changes somewhere (maybe in plugin-info extension).

[atsushieno]

This extension function is already landed in parameters.h. We would probably need some host implementation that can verify this functionality.

[atsushieno]

Looks like BYOD dynamically changes the parameter list, when it loads a preset model. We could implement the extension in aap-juce and verify the updates list using aap-juce-simple-host.

[atsushieno]

BYOD, as of the revision when aap-juce-byod was created, does not seem to send parameter info updates to the change listeners. The latest version might work, but if it's not the case then we should try something else like monique-monosynth which indeed calls AudioProcessor::sendParamChangeMessageToListeners()