More fixes

- Allow stock item creation for inactive parts
- Better handling of successful stock item creation
- Disable fields rather than hiding them

InvenTree/templates/js/translated/forms.js

@@ -25,6 +25,9 @@
 */
 
 /* exported
+    clearFormInput,
+    disableFormInput,
+    enableFormInput,
     hideFormInput,
     setFormGroupVisibility,
     showFormInput,
@@ -1261,6 +1264,23 @@ function initializeGroups(fields, options) {
     }
 }
 
+// Clear a form input
+function clearFormInput(name, options) {
+    updateFieldValue(name, null, {}, options);
+}
+
+// Disable a form input
+function disableFormInput(name, options) {
+    $(options.modal).find(`#id_${name}`).prop('disabled', true);
+}
+
+
+// Enable a form input
+function enableFormInput(name, options) {
+    $(options.modal).find(`#id_${name}`).prop('disabled', false);
+}
+
+
 // Hide a form input
 function hideFormInput(name, options) {
     $(options.modal).find(`#div_id_${name}`).hide();