fix: revert change from readonly to disabled on liaison from contact (ietf-tools#4708)

* feat: apply 'readonly' property to select2 inputs

* fix: revert change from readonly to disabled on liaison from contact

Author: jennifer-richards

ietf/liaisons/forms.py

@@ -510,7 +510,7 @@ def set_from_fields(self):
         else:
             email = self.person.email_address()
         self.fields['from_contact'].initial = email
-        self.fields['from_contact'].widget.attrs['disabled'] = True
+        self.fields['from_contact'].widget.attrs['readonly'] = True
 
     def set_to_fields(self):
         '''Set to_groups and to_contacts options and initial value based on user

ietf/static/css/select2.scss

@@ -3,3 +3,21 @@
 @import "bootstrap/scss/mixins";
 @import "select2/src/scss/core";
 @import "select2-bootstrap-5-theme/src/include-all";
+
+// Propagate readonly property from input to select2 instrumentation, based on
+// https://stackoverflow.com/questions/41807096/select2-make-it-readonly-not-disabled-from-js/55001516#55001516
+select[readonly].select2-hidden-accessible + .select2-container {
+  pointer-events: none;
+  touch-action: none;
+
+  .select2-selection {
+    background: $form-select-disabled-bg;
+    color: $form-select-disabled-color;
+    border-color: $form-select-disabled-border-color;
+    box-shadow: none;
+  }
+
+  .select2-selection__arrow, .select2-selection__clear {
+    display: none;
+  }
+}