Allow to clone an external repo before the build

Implemented solution:

the clone is done before the build, hence on skaffold and codefresh

The before-build hook is used on Skaffold

Additional clone steps are added on codefresh

How to test this PR: Add application git dependencies on values.yaml like

harness:
  dependencies:
    git:
    - url: https://github.com/MetaCell/nwb-explorer.git
      branch_tag: master
      path: nwbexplorer

to one of your applications (say myapp). Then run harness-deployment ... -i myapp -e dev and verify that:

skaffold.yaml has a new hook with a clone command
deployment/codefresh-dev.yaml is updated with a clone step for https://github.com/MetaCell/nwb-explorer.git

[x] The pull request is explicitly linked to the relevant issue(s)
[x] The issue is well described: clearly states the problem and the general proposed solution(s)
[x] From the issue and the current PR it is explicitly stated how to test the current change
[x] The labels in the issue set the scope and the type of issue (bug, feature, etc.)
[x] All the automated test checks are passing
[x] All the linked issues are included in one Jira sprint and release
[x] All the linked issues are in the Review/QA column state -- see backlog
[x] All the linked issues are assigned

[x] There is no reason why deployments based on CloudHarness may break after the current update
[ ] This PR and the issue are tagged as alert:deployment

MetaCell / cloud-harness