Migrate FPC internals from fabric-protos-go to fabric-protos-go-apiv2

[PsychoPunkSage]

Describe the bug
When running integration tests that combine FPC with FSC (Fabric Smart Client) in the same binary - such as integration/go_chaincode/echo and samples/demos/irb - the process panics at startup with:

  panic: proto: message rwset.TxReadWriteSet is already registered
          previously from: "github.com/hyperledger/fabric-protos-go/ledger/rwset"
          currently from:  "github.com/hyperledger/fabric-protos-go-apiv2/ledger/rwset"
  See https://protobuf.dev/reference/go/faq#namespace-conflict

This is a protobuf namespace conflict caused by two different packages defining the same proto message types being linked into the same binary.

To Reproduce

1. Clone the repo and check out main
2. Run the echo FSC integration test:

cd integration/go_chaincode
go test -v -failfast ./echo/...

3. Or run the IRB demo test:

cd samples/demos/irb
go test -v -failfast ./...

4. Observe panic: proto: message rwset.TxReadWriteSet is already registered

Expected behavior
Tests run without panicking. No duplicate proto message registration occurs.

Log-files/Screenshots

Logs

panic: proto: message rwset.TxReadWriteSet is already registered
	See https://protobuf.dev/reference/go/faq#namespace-conflict
	

goroutine 1 [running]:
google.golang.org/protobuf/reflect/protoregistry.init.func1({0x2e4d440?, 0x2e4a9e487ed0?}, {0x2e4d440, 0x2e4a9e487ed0})
	/home/psychopunk_sage/go/pkg/mod/google.golang.org/protobuf@v1.36.11/reflect/protoregistry/registry.go:56 +0x1e5
google.golang.org/protobuf/reflect/protoregistry.(*Types).register(0x2e4a9e5f6540, {0x2c76dc5, 0x7}, {0x2ea6160, 0x2e4a9e732008}, {0x2c45ae0, 0x2e4a9e697500})
	/home/psychopunk_sage/go/pkg/mod/google.golang.org/protobuf@v1.36.11/reflect/protoregistry/registry.go:579 +0x1c6
google.golang.org/protobuf/reflect/protoregistry.(*Types).RegisterMessage(0x2e4a9e5f6540, {0x2e7f950, 0x2e4a9e697500})
	/home/psychopunk_sage/go/pkg/mod/google.golang.org/protobuf@v1.36.11/reflect/protoregistry/registry.go:506 +0x11f
github.com/golang/protobuf/proto.RegisterType({0x2e81f30, 0x0?}, {0x2c97186, 0x14})
	/home/psychopunk_sage/go/pkg/mod/github.com/golang/protobuf@v1.5.4/proto/registry.go:181 +0x45
github.com/hyperledger/fabric-protos-go/ledger/rwset.init.0()
	/home/psychopunk_sage/go/pkg/mod/github.com/hyperledger/fabric-protos-go@v0.3.0/ledger/rwset/rwset.pb.go:353 +0x4b
FAIL	github.com/hyperledger/fabric-private-chaincode/integration/go_chaincode/echo	0.019s
?   	github.com/hyperledger/fabric-private-chaincode/integration/go_chaincode/echo/out/cmd/alice	[no test files]
?   	github.com/hyperledger/fabric-private-chaincode/integration/go_chaincode/echo/out/cmd/bob	[no test files]
?   	github.com/hyperledger/fabric-private-chaincode/integration/go_chaincode/echo/views	[no test files]
FAIL

Environment (please complete the following information):

• OS: Linux (Ubuntu 25.04)
• FPC Version: main (post PR Feat: fpc-fsc extension submodule #957)
• Go: 1.22+
• FSC: v0.11.0

Additional context
Root cause: Two separate import chains pull in conflicting proto packages into the same binary:

Chain	Package
client_sdk/go/pkg/core/contract → internal/utils	fabric-protos-go (old API)
fabric-smart-client/platform/fabric (FSC v0.11.0)	fabric-protos-go-apiv2 (new API)

Both packages define Fabric proto types (e.g. rwset.TxReadWriteSet) under the same proto message names, causing Go's global proto registry to panic.

Temporary workaround (applied in PR #957): GOLANG_PROTOBUF_REGISTRATION_CONFLICT=warn is set in the affected Makefiles, which is the officially documented bridge (https://protobuf.dev/reference/go/faq#namespace-conflict) for this migration scenario.

Proper fix: Migrate FPC's internal/utils, client_sdk/go, ercc, and ecc from github.com/hyperledger/fabric-protos-go to github.com/hyperledger/fabric-protos-go-apiv2. This aligns FPC with FSC v0.11.0+ and eliminates the dual-registration entirely. The migration requires updating all import paths and any proto type assertions across the affected packages.