Describe what happened

Usually Datadog will trigger application_start action event at first.
But when AddLongTask event was triggered as a first RUM event, application_start action event won't be triggered.

Steps to reproduce the issue:

Trigger any AddLongTask quickly when just Datadog initialized.

Sample: ken-kentan#2

Describe what you expected:

application_start action event should be triggered even if the first RUM event was AddLongTask.

I investigated around RumSessionScope and found than when AddLongTask event was triggered as a first event, sessionState was changed to State.EXPIRED, then RumSessionScope::handleEvent passed noOpWriter as an actualWriter for ApplicationStarted event.
I guess sessionState shouldn't be State.EXPIRED in this case.

Additional context

• Android OS version: N/A
• Device Model: N/A
• Datadog SDK version: 1.19.0-2.0.0
• Versions of any other relevant dependencies (OkHttp, …): N/A
• Proguard configuration: N/A
• Gradle Plugins: N/A

Note: This issue might be same with #1523