Add a new command that is able to return the set of configurations that that the
given instance of memgraph was started up with. The returned information
currently consists of the name, the default and the current value of each flag.
The hidden property of three flags were removed, namely --query-cost-planner,
--query-vertex-count-to-expand-existing and --query-max-plans. The flag
--log-link-basename was completely removed since it is not used.
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