Allow ability to verify host key for git clone of datadir using SSH protocol

[edevosc2c]

Cause

Currently, we do not verify the host key when doing a git clone of datadir using the SSH protocol: https://github.com/georchestra/helm-georchestra/blob/main/templates/_bootstrap-georchestra-datadir.tpl#L18
HTTPS (the default protocol when simply deploying the helm chart) is not affected, as it verifies the TLS certificate.

If someone manages to do a man in the middle between the Kubernetes cluster and the final git repository, then an attacker could provide malicious configurations to the pods.

Some possibilities by providing malicious configurations:

• allow doing some remote execution of some affected programs.
• deface the website
• show different data like their own metadatas and so on

Solution

We should allow the ability to provide a host key in the values.yaml file so that git verifies the git server.