[feature] Add support for profile fields (#1483)

* Add go-playground/form pkg

* [feature] Add support for profile fields

* Add field attributes test

* Validate profile fields form

* Add profile field validation tests

* Add Field Attributes definition to swagger

---------

Co-authored-by: tobi <31960611+tsmethurst@users.noreply.github.com>

internal/api/client/accounts/accountupdate.go

@@ -25,6 +25,7 @@ import (
 	"strconv"
 
 	"github.com/gin-gonic/gin"
+	"github.com/go-playground/form/v4"
 	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
 	apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
@@ -115,6 +116,13 @@ import (
 //		in: formData
 //		description: Enable RSS feed for this account's Public posts at `/[username]/feed.rss`
 //		type: boolean
+//	-
+//		name: fields_attributes
+//		in: formData
+//		description: Profile fields to be added to this account's profile
+//		type: array
+//		items:
+//			type: object
 //
 //	security:
 //	- OAuth2 Bearer:
@@ -162,6 +170,28 @@ func (m *Module) AccountUpdateCredentialsPATCHHandler(c *gin.Context) {
 	c.JSON(http.StatusOK, acctSensitive)
 }
 
+type fieldAttributesBinding struct{}
+
+func (fieldAttributesBinding) Name() string {
+	return "FieldAttributes"
+}
+
+func (fieldAttributesBinding) Bind(req *http.Request, obj any) error {
+	if err := req.ParseForm(); err != nil {
+		return err
+	}
+
+	decoder := form.NewDecoder()
+	// change default namespace prefix and suffix to allow correct parsing of the field attributes
+	decoder.SetNamespacePrefix("[")
+	decoder.SetNamespaceSuffix("]")
+	if err := decoder.Decode(obj, req.Form); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func parseUpdateAccountForm(c *gin.Context) (*apimodel.UpdateCredentialsRequest, error) {
 	form := &apimodel.UpdateCredentialsRequest{
 		Source: &apimodel.UpdateSource{},
@@ -171,6 +201,11 @@ func parseUpdateAccountForm(c *gin.Context) (*apimodel.UpdateCredentialsRequest,
 		return nil, fmt.Errorf("could not parse form from request: %s", err)
 	}
 
+	// use custom form binding to support field attributes in the form data
+	if err := c.ShouldBindWith(&form, fieldAttributesBinding{}); err != nil {
+		return nil, fmt.Errorf("could not parse form from request: %s", err)
+	}
+
 	// parse source field-by-field
 	sourceMap := c.PostFormMap("source")