Add support for automatically retrying and disabling broken storage plugins

Enabled storage plugins may malfunction for different reasons, e.g. they have been misconfigured or their remote data source has gone offline. Depending on the plugin's implementation, this could cause it to fail to return optimizer rules or register schemas. In some cases this can have a wider impact, e.g. unconditioned queries against the info schema will fail if a single plugin is failing in registerSchemas.

Rather than us swallowing such errors and silently returning a subset of results, this Jira proposes new features that allow firstly for the retrying of attempts to get rules or schemas from a plugin and secondly for a plugin to be automatically disabled after the configured maximum number of attempts have failed. A broken plugin will still cause a query failure but the user will be informed that the plugin has been disabled as a result. Knowing what has just happened, the user can choose to reissue the query knowing that the broken plugin is now disabled or they might choose to investigate the problem affecting the broken plugin instead.

These new features are optional and can be disabled using new SYSTEM options.