Enable TLS Encrypted ClientHello

Encrypted ClientHello (ECH) is an extension to TLS to encrypt sensitive fields of the ClientHello and improve privacy. If this policy is not configured, or is set to enabled, Brave will follow the default rollout process for ECH. If it is disabled, Brave will not enable ECH. When the feature is enabled, Brave may or may not use ECH depending on server support, availability of the HTTPS DNS record, or rollout status. ECH is an evolving protocol, so Brave's implementation is subject to change. As such, this policy is a temporary measure to control the initial experimental implementation. It will be replaced with final controls as the protocol finalizes.