[Analytics] Support setDefaultEventParameters

[ghost23]

In our app, we have a bunch of parameters, that we would like to track with every event (even the automatic ones). Currently we can only always manually attach those to our own tracked events.

The native Firebase Analytics SDKs recently got the new method setDefaultEventParameters:

https://firebase.google.com/docs/reference/ios/firebaseanalytics/api/reference/Classes/FIRAnalytics?hl=en#/c:objc(cs)FIRAnalytics(cm)setDefaultEventParameters:

https://firebase.google.com/docs/reference/kotlin/com/google/firebase/analytics/FirebaseAnalytics?hl=en#setdefaulteventparameters

For Android, this was introduced in version 17.5.0, for iOS, it was 6.29.0:

https://firebase.google.com/support/release-notes/ios#version_6290_-_july_28_2020
https://firebase.google.com/support/release-notes/android#analytics_v17-5-0

So my feature request is, please support this new method in the flutter firebase analytics sdk as well.