`NoVerifyServerName` disables sending SNI
When `TLSFlags.NoVerifyServerName` is specified, in `tlsstream.nim`, BearSSL is configured with `sslClientReset(res.ccontext, "", 0)`. While this disables server name verification, it also disables sending SNI, leading to connection failure when connecting to servers that require SNI extension to be present (e.g., Alchemy).

SNI extension should still be sent, even when `NoVerifyServerName` is specified.

(empty string seems to have same behaviour as NULL)
```
/**
 * \brief Prepare or reset a client context for a new connection.
 *
 * The `server_name` parameter is used to fill the SNI extension; the
 * X.509 "minimal" engine will also match that name against the server
 * names included in the server's certificate. If the parameter is
 * `NULL` then no SNI extension will be sent, and the X.509 "minimal"
 * engine (if used for server certificate validation) will not check
 * presence of any specific name in the received certificate.
 *
 * Therefore, setting the `server_name` to `NULL` shall be reserved
 * to cases where alternate or additional methods are used to ascertain
 * that the right server public key is used (e.g. a "known key" model).
 *
 * If `resume_session` is non-zero and the context was previously used
 * then the session parameters may be reused (depending on whether the
 * server previously sent a non-empty session ID, and accepts the session
 * resumption). The session parameters for session resumption can also
 * be set explicitly with `br_ssl_engine_set_session_parameters()`.
 *
 * On failure, the context is marked as failed, and this function
 * returns 0. A possible failure condition is when no initial entropy
 * was injected, and none could be obtained from the OS (either OS
 * randomness gathering is not supported, or it failed).
 *
 * \param cc               client context.
 * \param server_name      target server name, or `NULL`.
 * \param resume_session   non-zero to try session resumption.
 * \return  0 on failure, 1 on success.
 */
int br_ssl_client_reset(br_ssl_client_context *cc,
	const char *server_name, int resume_session);
```