feat: Enable configuration of offline mode on all platforms

[morzel85]

Plugin(s)

• Analytics
• App
• App Check
• Authentication
• Crashlytics
• Cloud Firestore
• Cloud Functions
• Cloud Messaging
• Cloud Storage
• Performance
• Remote Config

Current problem

Currently offline document read is not supported on Web platform. Executing this code:

const { snapshot } = await FirebaseFirestore.getDocument({
  reference: 'someDocPathHere',
});

Gives such error: "FirebaseError: Failed to get document because the client is offline"

Preferred solution

capacitor-firebase should expose configuration for enabling/disabling offline mode on all platforms where Firestore itself can support it.

Alternative options

No response

Additional context

#713

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