Add OperationDescription.SyncMethod, BeginMethod, and EndMethod

[t-palanis]

Describe the bug
Hi! We are migrating our legacy application in ,Net framework to .NET core and noticed that
OperationDescription.SyncMethod, BeginMethod, and EndMethod are missing from the .NET Core API but are available in the .NET framework version

Similar request to #4549. Would it be possible to expose these?

cc @mconnew

[mconnew]

We're locked in on the api surface that will be released for the upcoming 6.0 release. We can certainly add these, but it will be a while before they would be available to use. Can you describe a bit more about how you are using these properties? With the timing, if there's an alternative way to achieve your goal it might be better to modify your code to unblock you sooner.

[t-palanis]

@mconnew Thanks for the reply! From legacy, we have existing code to read custom attributes in service synchronization method(Syncmethod) via ContractDescription.Operations, currently unable to do so in .NET 6/7.

We don't have an immediate need and if this could be available in next few months, that would be helpful

[mconnew]

No , the async nature of the operation is irrelevant when sent across the network. A client can call APM, Sync, or Task and the server can be any one of the three (in wcf) or the two for CoreWCF.
I replied to the wrong issue about something unrelated.

[HongGit]

@imcarolwang can you please see if you could add these? In addition, please add tests for these APIs as well.