Bumps the sdk-golang dependency from v1 to the v2 module
(`github.com/openziti/sdk-golang/v2` at v2.0.0-pre1) and updates all
import paths. This is a no-behavior-change precursor that isolates the
dependency migration from the Connect-V2 feature work in #3884.
- Rewrites `github.com/openziti/sdk-golang/...` imports to
`github.com/openziti/sdk-golang/v2/...` across the main and zititest
modules.
- Pins both modules to `github.com/openziti/sdk-golang/v2 v2.0.0-pre1`.
- Adapts `edgeXgressConn.AcceptMessage` to the v2 `MsgSink` signature,
which now takes an `edge.SdkChannel` argument.
- Replaces the removed `edge.Conn.GetRouterId()` with
`RemoteAddr().String()` in the loop4 traffic-test logging.
For openziti/sdk-golang#936.
- moves the channel dependency to channel/v5 v5.0.10 and sdk-golang to v1.9.0 in the root and zititest modules
- mechanically rewrites every channel/v4 import path to channel/v5
This is the import-path-only step; the API-level changes the switch requires land in the following commit. This commit does not build on its own.