chore: add custom CA certificate injection

[olevski]

To properly do idle session culling amalthea needs to send a get request to https://<ful_session_path>/api/status.

In cases where self signed certificates are used this would fail without injecting these in amalthea.

[olevski]

<full_session_path> refers to what is usually the combination of <hostname>/sessions/<sesion_id> where the session can be accessed. I.e. it is the combination of the hostname and path in the ingress object created by amalthea.

[Panaetius]

Looks good