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/theme/OntimeAlert.ts

@@ -1,7 +1,7 @@
 export const ontimeAlertOnDark = {
   container: {
     fontSize: 'calc(1rem - 1px)',
-    backgroundColor: '#1a1a1a', // $gray-1300
+    backgroundColor: '#202020', // $gray-1200
     color: '#e2e2e2', // $gray-200
     borderRadius: '3px',
   },