feat(plugin): add rootca and tls verify for client http plugins

[adamwallred]

WHY

It would be nice to support a custom CA cert and perform TLS verification of the connections between the httputil.ReverseProxy and the proxied service in the client *2https plugins.

This PR adds support for loading a rootCA and verifying TLS connections for the client http plugins.

I manually tested this by adding an incorrect root CA cert and attempting to make use of the proxy:

and verify failed as expected.

After adding the proper root CA certificate, the verify and proxy worked as expected.

[github-actions[bot]]

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