[misc] Separate shared code dependencies (#4288)

* Separate shared code dependencies

* Fix import

* Test respective shared code

* Update openapi ref

* Fix test

* Fix test path

shared/relay/tls/doc.go

@@ -0,0 +1,36 @@
+// Package tls provides utilities for configuring and managing Transport Layer
+// Security (TLS) in server and client environments, with a focus on QUIC
+// protocol support and testing configurations.
+//
+// The package includes functions for cloning and customizing TLS
+// configurations as well as generating self-signed certificates for
+// development and testing purposes.
+//
+// Key Features:
+//
+//   - `ServerQUICTLSConfig`: Creates a server-side TLS configuration tailored
+//     for QUIC protocol with specified or default settings. QUIC requires a
+//     specific TLS configuration with proper ALPN (Application-Layer Protocol
+//     Negotiation) support, making the TLS settings crucial for establishing
+//     secure connections.
+//
+//   - `ClientQUICTLSConfig`: Provides a client-side TLS configuration suitable
+//     for QUIC protocol. The configuration differs between development
+//     (insecure testing) and production (strict verification).
+//
+//   - `generateTestTLSConfig`: Generates a self-signed TLS configuration for
+//     use in local development and testing scenarios.
+//
+// Usage:
+//
+// This package provides separate implementations for development and production
+// environments. The development implementation (guarded by `//go:build devcert`)
+// supports testing configurations with self-signed certificates and insecure
+// client connections. The production implementation (guarded by `//go:build
+// !devcert`) ensures that valid and secure TLS configurations are supplied
+// and used.
+//
+// The QUIC protocol is highly reliant on properly configured TLS settings,
+// and this package ensures that configurations meet the requirements for
+// secure and efficient QUIC communication.
+package tls