[FR]: setDefaults option without replace all

[4rthurmonteiro]

Description

Add the possibility to update setDefaults without replace the old ones if keys aren't the same.

How would you use it?

I'm using the add-to-app implementation and the host app already has defaults values. But in the flutter side I want add more defaults and I don't want add these defaults in android app code.

I opened a issue in firebase/flutterfire#17620 but firstly this feature must be available in the native SDK.

API Proposal

(void)setDefaults:(nullable NSDictionary<NSString *, NSObject *> *)defaults
            replace:(BOOL)replace;

if replace false the new parameters will be added with the old ones. If true, it will be replaced.

Firebase Product(s)

Remote Config

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.