Enrich every event with device and app context

[philipphofmann]

Currently, the SentryCrashIntegration configures the Scope of the current Hub with the device and app data.

sentry-cocoa/Sources/Sentry/SentryCrashIntegration.m

Lines 133 to 136 in b46bdab

	if (nil != [SentrySDK.currentHub getIntegration:integrationName]) {
	[SentrySDK.currentHub configureScope:^(SentryScope *_Nonnull outerScope) {
	// OS
	NSMutableDictionary *osData = [NSMutableDictionary new];

This has the disadvantage when creating a Hub manually the client doesn't enrich the event with device and app data. Java uses an EventProcessor to achieve this.

This came up because we made Sentry.currentHub private in 7.0.0 and a user used this method just to initialize a Hub with the scope of the currentHub, see #434 (comment).

[marandaneto]

using an EventProcessor also has its disadvantages, these trade-offs should be discussed before going forward though.

[philipphofmann]

Instead of using an event processor, we could do this in prepare event

sentry-cocoa/Sources/Sentry/SentryClient.m

Line 418 in b1ce7c5

- (SentryEvent *_Nullable)prepareEvent:(SentryEvent *)event