LogManager API status codes

[maxgolov]

There are several scenarios where LogManager returns STATUS_SUCCESS without actually checking:

• Flush
• Upload
• PauseTransmission
• ResumeTransmisison
• etc

Need to see where it is practical to add valid actual status code and return these as-needed. This is not about tracking async-future result code, this is about whether the op (e.g. upload) triggered and running or cannot be triggered. Right now we do not provide future-style tracking of async operations. These can only be tracked using Debug Event callback mechanism.

[maxgolov]

NOT necessarily status codes as in HRESULT, but need to come up with clean strategy..