fix: 解决golint 部分警告 (#897)

* feat:  解决goreportcard的警报
ps: warning: if block ends with a return statement, so drop this else and outdent its block (golint)

* feat: 优化golint警告，将processFieldPrimitiveWithJsonNumber 改成 processFieldPrimitiveWithJSONNumber
unmarshaler.go:248:23: method processFieldPrimitiveWithJsonNumber should be processFieldPrimitiveWithJSONNumber

* feat: 添加 WithCanonicalKeyFunc 注释

* feat: 添加DisableStat的注释

* feat: 添加 RegisterGoctlHome 注释

* feat: 添加 PostgreSqlJoin 注释

* feat: 解决goline警告should not use basic type string as key in context.WithValue问题

* feat: 解决golint警告信息： should not use basic type string as key in context.WithValue

* fix: 定义自定义字段类型，导致go test fail 问题

* update: 恢复原有测试用例

* fix golint warning

core/contextx/unmarshaler_test.go

@@ -8,6 +8,7 @@ import (
 )
 
 func TestUnmarshalContext(t *testing.T) {
+
 	type Person struct {
 		Name string `ctx:"name"`
 		Age  int    `ctx:"age"`
@@ -47,9 +48,11 @@ func TestUnmarshalContextWithMissing(t *testing.T) {
 		Name string `ctx:"name"`
 		Age  int    `ctx:"age"`
 	}
+	type name string
+	const PersonNameKey name = "name"
 
 	ctx := context.Background()
-	ctx = context.WithValue(ctx, "name", "kevin")
+	ctx = context.WithValue(ctx, PersonNameKey, "kevin")
 
 	var person Person
 	err := For(ctx, &person)

core/contextx/valueonlycontext_test.go

@@ -9,7 +9,9 @@ import (
 )
 
 func TestContextCancel(t *testing.T) {
-	c := context.WithValue(context.Background(), "key", "value")
+	type key string
+	var nameKey key = "name"
+	c := context.WithValue(context.Background(), nameKey, "value")
 	c1, cancel := context.WithCancel(c)
 	o := ValueOnlyFrom(c1)
 	c2, cancel2 := context.WithCancel(o)