Add API version constant to generated code (#3439)

* Add API version constant to generated code

This commit introduces the "APIVersion" constant into the generated code. This addition enables the utilization of this value in configuring telemetry data, complementing the existing "ServiceName" constant.

Additionally if a version isn't explicitely set in the design it is now defaulted to "0.0.1".

* Update to latest v3

codegen/service/service.go

@@ -334,6 +334,9 @@ type Auther interface {
 // key.
 const ServiceName = {{ printf "%q" .Name }}
 
+// APIVersion is the version of the API as defined in the design.
+const APIVersion = {{ printf "%q" .APIVersion }}
+
 // MethodNames lists the service method names as defined in the design. These
 // are the same values that are set in the endpoint request contexts under the
 // MethodKey key.

codegen/service/service_data.go

@@ -41,6 +41,8 @@ type (
 		Name string
 		// Description is the service description.
 		Description string
+		// APIVersion is the API version.
+		APIVersion string
 		// StructName is the service struct name.
 		StructName string
 		// VarName is the service variable name (first letter in lowercase).
@@ -747,6 +749,7 @@ func (d ServicesData) analyze(service *expr.ServiceExpr) *Data {
 	data := &Data{
 		Name:               service.Name,
 		Description:        desc,
+		APIVersion:         expr.Root.API.Version,
 		VarName:            varName,
 		PathName:           codegen.SnakeCase(varName),
 		StructName:         codegen.Goify(service.Name, true),