feat: HTTPS server skeleton

[kayra1]

Description

This change introduces some helper functions and initialization code to have a barebones https server up with external private key and certificates.

This PR is introducing:

• The setup functionality for a net/http webserver,
• The logic to load a user provided certificate to the webserver,
• Tests to validate the behaviour of all of these features,
• Command line options that will be useful in production.

The command line for GoCert accepts 1 mandatory argument:

• --config receives the path for a YAML file that describes the following variables:
  • KeyPath is the path for a private key of a x.509 certificate,
  • CertPath is the path for a x.509 certificate,
  • DBPath is the path for a file for SQLite to use,
  • Port is an integer for which port the service will be deployed in,

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that validate the behaviour of the software
• I validated that new and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[kayra1]

I've tried to be consistent with capitalization in errors and specifying RSA private key instead of just private key, but I may have slipped somewhere. Please let me know if you see any inconsistencies.

[gruyaume]

looks good, make sure the pr description matches with its newer content. Here I'm referring to the fact we don't generate certs anymore.