Persist events to disk by default (offline caching)

[bruno-garcia]

The .NET SDK offers offline caching through.

Rely on Application.persistentDataPath to get a consistent path. A hash of the DSN should be used to get the path in order to make sure that events don't get mixed up if the DSN changes.

https://docs.sentry.io/platforms/dotnet/configuration/options/#cache-directory-path

We should also add to SentryWindow a way to configure this. How/why needs some thinking but some random thoughts:

• Opt-out of offline caching
• Opt-out from blocking app startup in order to flush cached events
  • This should have some big tooltip of sorts describing why it exists. If the app crashes on start, it's the only way to make sure the developer is aware.
• Change path where the files get cached. (Should this affect the DSN-hash-based prefix?)

The Xamarin SDK uses Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)

[bitsandfoxes]

Offline caching has been implemented. But there are some things to note:

• DSN is not part of the path
• The path can only be manipulated via code (since Unity provides persistent data path)
• Does not work on Nintendo Switch and leads to app crash because FileWrite & Application.persistentDataPath seem unsupported

[bruno-garcia]

Offline caching has been implemented. But there are some things to note:

• DSN is not part of the path

That part is done by the .NET SDK already, we don't need to worry here.

• The path can only be manipulated via code (since Unity provides persistent data path)

Worth adding a note on the docs but that's OK. Other than potentially related to #290

• Does not work on Nintendo Switch and leads to app crash because FileWrite & Application.persistentDataPath seem unsupported

True. We need to figure this one out.

The offline support is done though so I'll close this. The Switch issue can be tracked on #290