Add the ability to configure volume implementation

[sleshchenko]

Is your feature request related to a problem? Please describe.
Default volume implementation should be like PVC, but there are cases for other types, like emptyDir.
Empty dir case: some containers need to bring some binaries to others. For Che has a remote plugin launcher binary that is propagated to sidecars.

Describe the solution you'd like
It addition to size we can define backend:

components:
  - name: remote-injector
    volume:
      size: 100Mib
      emptyDir: {}

Describe alternatives you've considered
¯_(ツ)_/¯

Maybe something like Che has

components:
  - name: remote-injector
    volume:
      size: 100Mib
      temporary: true

Additional context
Add any other context or screenshots about the feature request here.

[l0rd]

@sleshchenko can we close this one?

[sleshchenko]

it's implemented by #324