Make the `RegisterClientArgs` a `parcelable` instead of an `interface`

This is to ensure we can have fully oneway logic in this interface.

This simplifies the code and improves performance by avoiding the overhead of binder calls for each getter method.

Test: atest TracingTests
Bug: 395688856
Flag: android.tracing.client_side_proto_logging
Change-Id: I3e1d2c73a8de76fbaff535e5570953c0c07a0b8b