feat(abci/server): accept pre-bound listener in socket and gRPC servers

[songgaoye]

Summary

• Add NewSocketServerWithListener and NewGRPCServerWithListener constructors to the ABCI socket and gRPC servers, following the same convention as net/http.Serve and grpc.Server.Serve
• OnStart skips net.Listen when a listener is already set, so both constructors share the same start path

Motivation

The existing constructors always call net.Listen inside OnStart, which has two drawbacks:

• TOCTOU: there is a race between selecting a port and binding it — another process can grab the port in that window. A pre-bound listener eliminates the race entirely.
• Testability: tests must pick a fixed port upfront, risking conflicts in parallel runs. With net.Listen("tcp", "127.0.0.1:0") the OS assigns an ephemeral port, and the caller knows the exact address before the server starts.

Socket-activated processes (e.g. systemd) also rely on passing pre-bound file descriptors, which this enables.

Test plan

• TestNewSocketServerWithListener: binds an ephemeral port, starts the server via the new constructor, dials it, stops cleanly
• TestNewGRPCServerWithListener: same pattern for the gRPC server
• Existing tests continue to pass