Move Service Discovery into dotnet/extensions after Aspire v1

[danmoseley]

[danmoseley]

@ReubenBond what is your thinking here -- and timeframe?
cc @joperezr

the repo will ship stable (and preview) packages every month which gives us flexibility...

[davidfowl]

I think we should move it when we ship v1 of aspire.

[gdantuono]

@danmoseley I hope you can move in new repository before Aspire GA