[Twenty CRM] Add regex pattern validation support for custom fields

## Scope & Context We are working with custom fields on People and Companies objects in Twenty CRM. This ticket is about adding regex pattern validation support when creating or editing custom fields in a workspace. Currently, Twenty CRM allows users to create custom text fields for objects (e.g., a "License Plate" field on People), but there is no way to enforce a specific format or pattern on the input. This is already supported in other platforms like Chatwoot's custom attributes, which allow defining a regex pattern and a hint message. ## Current behavior When creating a custom field for an object (e.g., People or Companies), the user can set a name, type, and description — but there is no option to define a validation pattern or regex for the field value. This means that a field like "License Plate" (expected format: 3 uppercase letters + 3 digits, e.g. `ABC123`) accepts any arbitrary string with no validation, leading to inconsistent data quality across contacts. <img width