[Bug]: Protobuf emitter incorrect map value type

[RobertVillalba]

Describe the bug

The protobuf emitter drops the package prefix from the map value type for maps that use an imported model as the value.

message MyLocal {
  map<string, Dummy> m = 1;
}

service MyServices {
  rpc Echo(MyLocal) returns (myshared.Dummy);
}

Reproduction

https://typespec.io/playground?c=aW1wb3J0ICJAdHlwZXNwZWMvcHJvdG9idWYiOw0KDQp1c2luZyBUeXBlU3BlYy5Qxx3FHEBwYWNrYWdlKHsNCiAgbmFtZTogIm15c2hhcmVkIiwNCn0pDQrEF3NwYWNlIE15U8UaIMUvbW9kZWwgRHVtbXnGESAgQGZpZWxkKDEpIHg6IHN0cmluZzvEGn0NCn3ccGVydmljZdVxxhvMck15TG9jYWzSdG06IE1hcDzGeCzpAK4u5QCjPucAiMQHQOgBBS7HesQVaW50ZXJmzXZzyGRlY2hvKC4uLsd7KTrPXesA5Q%3D%3D&e=%40typespec%2Fprotobuf&options=%7B%7D

Checklist

• Follow our Code of Conduct
• Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion.
• The provided reproduction is a minimal reproducible example of the bug.

[witemple-msft]

Thank you for reporting this issue. The same logic that applies to return types and property types for resolving cross-package references was missed in the calculation of map value types. The following PR will resolve this issue: #3561