License keys are not kept out of logs, and the data update messages name the URL that carries them #51

What happens

The URL a data update request is sent to carries the license keys in its query. The data update logging section gives messages that name that URL, such as "Checking for update from '<url>'" (lines 399 to 401) and the connection and download errors (lines 417 to 418). The logging feature says nothing about credentials. Following the specification therefore writes the license keys to the log.

The .NET pipeline logs the URL with the keys at Information level on every check (DataUpdateService.cs line 1192). The Java pipeline logs it at debug level on every download and at error level on every failed one (DataUpdateServiceDefault.java lines 595 to 640). The Rust SDK put them in its error messages.

What is needed

1. The logging feature to say a license key never appears in a log entry or an error message, and that a message naming a URL that carries one names it with the key removed or replaced.
2. The data update logging section to say the same of its <url>.

The change is #55. The Rust SDK's change is 51Degrees/51degrees-rust#175.