feat: Custom TLS certificate support

[DanielHougaard]

This PR introduces support for custom / self-signed certificates that aren't present in the root store or webPKI store.

The user is given two options on how they want to pass in the certificate

1. The path to the certificate. This is passed when initializing the Infisical client in the respective language.
2. An environment variable containing the full certificate. If no path is provided, we check internally for an environment variable containing the certificate.

There are quite a few files changed, because we need to ensure all the requests being sent by the SDK is covered by the TLS support.

There's a new build_minimal_base_request function, which doesn't factor in the SSL certificate. This function is used when sending requests to non-Infisical hosts like GCP or AWS.