add mitm and mtls protection

[valdo404]

description:

• add mutual TLS authentication on the proxy socket
• reject the request when user is not authenticated (it includes full certification chain)
• automatically build certificates using let's encrypt crates, for server side
• use private automated CA for private side
• improve provided proxy.pac with mutual TLS endpoint

[valdo404]

missing implementation.

mtls is detected but not enforced. need to pass the incoming certificate and to validate it