Support Azure MySQL (#8618)
Support Azure MySQL (#8618)

Azure's MySQL implementation appears to always respond with an Authentication Method Switch Request Packet requesting `mysql_native_password` auth even though the client's initial Handshake Response already included the native password credentials.

Most MySQL client libraries support this but Golang's go-sql-driver/mysql requires the `allowNativePasswords` DSN parameter set to enable it. Without this parameter, Grafana fails to authenticate to the database with the error message "this user requires mysql native password authentication."

References:

* https://web.archive.org/web/20160814002743/http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::AuthSwitchRequest
* https://web.archive.org/web/20160814002743/http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::HandshakeResponse
* https://github.com/go-sql-driver/mysql#user-content-allownativepasswords
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