fix: Data browser filters "key exists" and "key does not exist" not working (#2760)

Author: mtrezza

src/lib/Filters.js

@@ -112,15 +112,15 @@ export const Constraints = {
   },
   keyExists: {
     name: 'key exists',
-    field: 'Object',
+    field: 'String',
     composable: true,
-    comparable: false,
+    comparable: true,
   },
   keyDne: {
     name: 'key does not exist',
-    field: 'Object',
+    field: 'String',
     composable: true,
-    comparable: false,
+    comparable: true,
   },
   keyEq: {
     name: 'key equals',
@@ -169,13 +169,11 @@ export const FieldConstraints = {
   Pointer: ['exists', 'dne', 'eq', 'neq', 'starts', 'unique'],
   Boolean: ['exists', 'dne', 'eq', 'unique'],
   Number: ['exists', 'dne', 'eq', 'neq', 'lt', 'lte', 'gt', 'gte', 'unique'],
-  String: ['exists', 'dne', 'eq', 'neq', 'starts', 'ends', 'stringContainsString', 'unique'],
+  String: ['exists', 'dne', 'eq', 'neq', 'starts', 'ends', 'stringContainsString', 'unique', 'keyExists', 'keyDne'],
   Date: ['exists', 'dne', 'before', 'after', 'unique'],
   Object: [
     'exists',
     'dne',
-    'keyExists',
-    'keyDne',
     'keyEq',
     'keyNeq',
     'keyGt',