Make `MySqlConnectorLogManager.Provider` `[Obsolete]`

[bgrainger]

trafficstars

MySqlConnectorLogManager.Provider is "deprecated" in MySqlConnector 2.3.0: https://github.com/mysql-net/MySqlConnector/blob/413b4bb5e231e9115c1018bc5af85115c4940123/docs/content/overview/version-history.md#L43

However, the property hasn't been marked [Obsolete] in code: https://github.com/mysql-net/MySqlConnector/blob/413b4bb5e231e9115c1018bc5af85115c4940123/src/MySqlConnector/Logging/MySqlConnectorLogManager.cs#L15

In a future release (maybe 2.4.0?), this property should be marked [Obsolete] with more direct guidance to users to use AddMySqlDataSource or UseLoggerFactory.