feat: add experimental message identifiers flag

[GeekyEggo]

Stream Deck 7.1 introduces the ability to identify "get" events, such as:

• getSettings and didReceiveSettings
• getGlobalSettings and didReceiveGlobalSettings.

This is particularly useful as it allows Makers to determine when/why the onDidReceiveSettings event occurred, i.e. was it because the settings were requested or was it because the settings were updated in the property inspector.

As Stream Deck 7.1 adoption is early, we cannot yet rely on message identifiers, and changing event propgagation throughout would result in a change in behaviour. To overcome this, this pull request adds the options to opt in to message identifiers, which:

• When enabled (true) - onDidReceiveSettings and onDidReceiveGlobalSettings are only called when the settings are updated from the property inspector.
• When disabled (false, default) - onDidReceiveSettings and onDidReceiveGlobalSettings are called when the settings are requested or udpated from the property inspector (current behaviour).