Catch bad FractionConsumed values in the beam SDK.

[kennknowles]

getFractionConsumed in Sources are expected to return values between 0.0 and 1.0

I recently encountered a bug where a bad value of fractionConsumed was sent to a runner. Looking through the beam source, I couldn't find anywhere that we validate the value before we send it (it could be there and I didn't see it, but given that I saw this error with a real source, I don't believe it is.)

I think it'd be useful if the beam SDK caught this error at the time the value is returned and at least generate a useful error in the logs (thus allowing the user to more easily debug the issue)

Imported from Jira BEAM-1639. Original Jira may contain additional context.
Reported by: sisk.