Ability for API to Lock Native and/or Custom Fields

[#1]

When using an API call to populate native and/or custom fields at the task level, it would be nice if the call could also lock the fields to indicate changes are not possible by the users in Workfront. This allows the external system to remain the source of truth and eliminates the need to provide data mappings for each integration with WF so that users know what fields not to make changes to.

The lock should only apply to those tasks to which the API call affects rather than all tasks in a project, portfolio, etc.