Allow estimates to be updated using the Develop Model API

Who would benefit?

Users that create extensions to integrate with other dev tools

What impact would it make?

Allow to keep more details in sync

How should it work?

The Model API for doesn't allow providing estimates when creating a feature or requirement when importing items from dev tools. It forces people to manually update estimates after the import is done. Also, if an estimate changes in the dev tool, it's impossible to send the update to Aha! Develop using extensions webhook because the update of estimates isn't supported.

The issue can be esily resolved by allowing to provide estimates when creating features and requirements using the Model API, as well as support updating estimates.