Add support for CA/Private CA certs for supporting SSL/TLS based DB connections

[abhishek-centrica]

As a Dev/DBA team I can restrict DB instance to only allow SSL/TLS based DB connections. In that case the database client in DB2REST layer would need to support the custom certificates to be able to communicate to the database instance. In both desktop and docker installations an extension is expected to support this feature.

[kdhrubo]

Marked this as experimental may require some POC. Not sure at this moment. We can try it out on DigitalOcean as it requires a connection over SSL/TLS. For custom certificates, I am not sure may be tested on AWS.

[souravroy]

Can we do the POC with a certificate issues by Hashicorp vault which we can start as a docker container in local or run as desktop application? We need to configure vault which takes some effort.

[kdhrubo]

Hashicorp vault is a secret management tool.

I believe this is easy to do JDBC drivers support it already. Pvt CA certs will check. We can use lets encrypt to create cert but key is for DB provider to allow installing those certs

[kdhrubo]

@abhishek-centrica @souravroy ran into this trouble with cockroachdb / pgsql

[kdhrubo]

Need to update documentation