App files under src dir

[kquerna]

Description

For some teams, it is preferable to store app app code under a /src directory.
Currently, special directories need to be at the root of the repo. We should tune
this up to also allowing placing these under the /src.

Package(s): @gasket/cli, @gasket/plugin-lifecycle, *

AC:

• Identify where special files are looked up
• Ability to place special files under /src directory