net.ssl: switch to mbedtls over openssl (#15841)

vlib/net/ssl/ssl_d_use_openssl.v

@@ -0,0 +1,18 @@
+module ssl
+
+import net.openssl
+
+pub struct SSLConn {
+	openssl.SSLConn
+}
+
+[params]
+pub struct SSLConnectConfig {
+	openssl.SSLConnectConfig
+}
+
+// new_ssl_conn returns a new SSLConn with the given config.
+pub fn new_ssl_conn(config SSLConnectConfig) ?&SSLConn {
+	c := openssl.new_ssl_conn(config.SSLConnectConfig) or { return err }
+	return &SSLConn{c}
+}