[OSJC-101] Add support for setting and retrieving additional gear storag...

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I would not add a state to StandaloneCartridge. The initial aim of StandaloneCartridge was to have a definition to identify standalone cartridges. An "id"/"name" is not enough since there are also downloadable cartridges. Now that we introduce deployed standalone cartridges we should leave the definition alone and only add stateful information in StandaloneCartridgeResource imho