Plugin web API refactor onCreateTask to allow returning inputs instead of DialogContent component

[richardguerre]

Context

The web.onCreateTask API currently allows plugins to show a Dialog to prompt the user to input more data about the task.

• For example, the GitStart plugin, asks the user to input the task title (defaults to the same title as the item they are creating the task from), the GitStart initial task status, and the GitStart task type.
• If there are multiple plugins that need to prompt the user for additional data, the dialogs are shown one after the other.
  • This can be tedious for users and it would more concise to ask everything in one form.
• For a lot of plugins, they are asking additional metadata for the task, and would simply require adding an input like a dropdown to an existing form.
• This is the example in the "Flow 1.0" project description for what is not stable about the Plugin API, hence why it is part of the "Flow 1.0" project.

Solution

• Allow plugins to return DialogInput components so they can be rendered as part of Flow's native Create task dialog.
• Still allow plugins to return DialogContent components so they can still prompt the user for additional content within their own dialog.