* Server: make the `health` endpoint more useful by adding more status checks to it.
* Server: parse `retry_schedule` as an array rather than string.
* People should use the next syntax: `[1, 2]`, though the old syntax is still supported for backwards compatibility.
* Server: add validation to ensure endpoint URL scheme is either http or https.
* Libs/Python: show a more useful error for obviously malformed secrets.
* Libs/JavaScript: show a more useful error for obviously malformed secrets.