Adds AmplifyTask and Task Adapter for Operations

[brennanMKE]

Issue #, if available:

Description of changes:

Amplify V2 will have an async API and encapsulate Operations as an internal implementation. AmplifyTask will define the public API for Tasks. Operations are given to ChildTask to provide async properties result and progress.

Check points: (check or cross out if not relevant)

• [ ] Added new tests to cover change, if needed
• [ ] Build succeeds with all target using Swift Package Manager
• [ ] All unit tests pass
• [ ] All integration tests pass
• [ ] Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• [ ] Documentation update for the change if required
• [ ] PR title conforms to conventional commit style
• [ ] If breaking change, documentation/changelog update with migration instructions

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.