Support grpc-swift 2.x

[tweidema]

First, thank you so much for making swift-otel available! It has been an invaluable resource in my first steps with Swift and distributed tracing.

The grpc-swift project has branched release 1 to release/1.x and use main for a major rewrite. "gRPC Swift v2.x is under active development on the main branch and takes full advantage of Swift's native concurrency features." They released 2.0.0-alpha.1 2 weeks ago.

I would like to request support for this release in swift-otel.