Certificate Part 3: Add Generate Certificate Endpoint

[lydiazcheng]

Changes

This PR adds 2 new endpoints:

1. generate root certificate
   • either create a self signed root certificate and a sub CA
   • or only create a sub CA and sign it by an external ca root certificate (use acme client and Let'e encrypt root cert)
2. install root certificate to charger.
   • if fileId is set in the request body, this endpoint will install the given file to charger
   • if not, the endpoint will get the external root CA according to the certificate type, e.g., if certificateType is V2GRootCertificate, it get root CA from hubject and install it.

Local Test

Test case 1: create self signed root CA and sub CA

1. call endpoint and get the generated certificate entities in the response body.
2. generated certs and keys are stores in directus files

Test case 2: install root certificate to charger

1. install self signed CSMSRootCertificate:
2. install external CSMSRootCertificate from Lets encrypt
3. install external V2GRootCertificate from hubject

Test case 3: create sub CA signed by external CA server TBD

Test case 4: Everest connect to Citrine using self signed root CA without no matched ciphers error TBD