make custom fields case sensitive (#1242)

* remove custom field lowercasing

* don't allow custom field form to submit duplicate field

* remove unused

* update custom field tests

* also keep upper case when editing

* show key in UI

* also kep upper case when creating a new field

* fix test

* allow old forced case keys to stay as is

* allow space

* add extension to import

* supply initial key to CustomFieldForm

* refactor: improve element contrast

* refactor: style and composition

* consistent use of `customFieldLabelToKey`

* fix CopyTag

* remove log

---------

Co-authored-by: arc-alex <ac@omnivox.dk>
Co-authored-by: Carlos Valente <carlosvalente@pm.me>

apps/client/src/features/app-settings/panel/feature-settings-panel/FeatureSettings.module.scss

@@ -1,3 +1,7 @@
+.halfWidth {
+  width: 50%;
+}
+
 .fullWidth {
   width: 100%;
 }
@@ -37,3 +41,9 @@
 .flex {
   display: flex;
 }
+
+.twoCols {
+  display: grid;
+  grid-template-columns: 1fr 1fr;
+  gap: 1rem;
+}