[go] More idiomatic godoc comments (#10044)

* [go] More idiomatic godoc comments

* [go] Mark deprecated fields and functions

* [go] Minor mustache readability/consistency fixes

* [go] Mark deprecated operation parameters

* [go] Deprecate a petstore component property for testing

* [go] Apply deprecated godoc in Go servers also

samples/server/petstore/go-gin-api-server/go/api_pet.go

@@ -31,6 +31,7 @@ func FindPetsByStatus(c *gin.Context) {
 }
 
 // FindPetsByTags - Finds Pets by tags
+// Deprecated
 func FindPetsByTags(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{})
 }