Propagation in case of remote parent

[vishweshbankwar]

Currently, TraceProviderSDK forces activity creation by returning PropagationOnly sampling result for root activities by checking
isRootSpan = traceId == default. However, in case of remote parent the traceId is not default (e.g. asp.net core request with traceparent) which will result in loss of context propagation if the sampling results in data drop.

Proposing to add isRemote check as well so that the incoming traceId can be propagated to next hop.

#3310 covers the unit test for the scenario. Will create a follow up PR of TracerProviderSDK changes.