Generic way to run extension commands when creating projects

[makandre]

**Codewind version:**0.4.0
OS:

Che version:
IDE extension version:
IDE version:
Kubernetes cluster:

Description of the enhancement:

This item is a follow-up to #270. For 0.4.0 due to time constraints the call to extension command appsody (as well as the detection of appsody projects (see: #445)) was hardcoded into the CLI.

This should be made generic to avoid hardcoding appsody logic into the CLI, which would also benefit future extensions. It is also a requirement for #292, because we will need to define an additional way to run appsody init, with arguments for the binding a vanilla project scenario.

Proposed solution:

As proposed in #270, we would allow an extension to define commands in its commands array:

commands:
  - name: postProjectValidate
    command: appsody
    args:
      - init

Then in the validate method of the CLI, it retrieves the extensions info PFE has loaded via GET /api/v1/extensions API. CLI then uses this to (in a generic manner) detect whether a project is an appsody project, and if so, run any applicable commands defined by the extension.

[makandre]

This would fix bug #445 in the process

[sghung]

Closing as it has been implemented