feat: Support Regex validation for custom attributes (#7856)

This allows a user to add/update a custom regex and a cue while defining custom attributes(Only applicable for type- text).
While adding/editing custom attributes, the values are validated against the attribute definition regex, and if it is incorrect, a cue message or default error message is shown and restricts invalid values from being saved.

Fixes: #6866

app/javascript/dashboard/helper/preChat.js

@@ -47,6 +47,8 @@ export const getCustomFields = ({ standardFields, customAttributes }) => {
         type: attribute.attribute_display_type,
         values: attribute.attribute_values,
         field_type: attribute.attribute_model,
+        regex_pattern: attribute.regex_pattern,
+        regex_cue: attribute.regex_cue,
         required: false,
         enabled: false,
       });