Allow user configuration of built-in workflows

[erinknight242]

Add a Settings menu option that opens a page that allows you to customize which metadata fields are visible (can list the available fields with checkboxes and have them checked by default), and also have a text input to allow the user to specify default values for any field. They should be able to specify required properties for the contract string (using a contract grid editor).

Options that can be configured: Visible (checkbox), Required (checkbox)

Fields that "Visible" is checked and disabled (can't hide these fields):
Description, Contract, Version Number

Acceptance criteria

• A user can configure the settings for a default Messaging contract
• A user can configure the settings for a default API contract
• Creating a new messaging or API contract uses the configured default values
• Default settings for Messaging includes required fields for Type and Namespace, and minimum contract string of ID and Timestamp
• Validation for creating or editing a contract string must match it's workflow **If a contract was created under WorkflowA, which was then changed to have different required fields, any messages tested against that contract would still treat the contract as valid, but attempting to edit the contract would require you to match the new workflow criteria.