RUMM-987 Add scrubbing API to DatadogObjc

[ncreated]

What and why?

📦 Based on RUM @objc models generated in #382, this PR adds Scrubbing APIs to DatadogObjc:

// in DDConfigurationBuilder:

@objc
public func setRUMViewEventMapper(_ mapper: @escaping (DDRUMViewEvent) -> DDRUMViewEvent?)

@objc
public func setRUMResourceEventMapper(_ mapper: @escaping (DDRUMResourceEvent) -> DDRUMResourceEvent?)

@objc
public func setRUMActionEventMapper(_ mapper: @escaping (DDRUMActionEvent) -> DDRUMActionEvent?)

@objc
public func setRUMErrorEventMapper(_ mapper: @escaping (DDRUMErrorEvent) -> DDRUMErrorEvent?)

How?

As usual, DatadogObjc APIs bridge their calls to Datadog (Swift).

I also made sure those APIs are properly exposed, compile and look "nice" in Objective-c. Here, an example of redacting the resource.url for POST resources and dropping all other resources:

[builder setRUMResourceEventMapper:^DDRUMResourceEvent * _Nullable(DDRUMResourceEvent * _Nonnull event) {
    if (event.resource.method == DDRUMResourceEventResourceRUMMethodPost) {
        event.resource.url = @"redacted";
        return event;
    } else {
        return nil;
    }
}];

Review checklist

• Feature or bugfix MUST have appropriate tests (unit, integration)
• Make sure each commit and the PR mention the Issue number or JIRA reference

[acgh]

That's quite straightforward thanks to your previous PR #382 👏