refactor!: FileSystemStore to use StoreKey

[varshith257]

Description

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include relevant motivation and context.

Fixes # (issue)

Type of change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• This change requires a documentation update

How Has This Been Tested?

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Checklist

• Updated documentation if needed
• Tests added/amended
• bazel test //... passes locally
• PR is contained in a single commit, using git amend see some docs

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[CLAassistant]

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[KGrewal1]

Dear any reviewers, can it please be acknowledged that I have had an open, complete pull request for this bounty for the previous 2 weeks (#1489) with pushes being to keep it up to date with main, with the difference being addition of a solution to needing excess clones for the map. Whilst I appreciate there are only so many ways to come to a solution to this issue and most will inevitably look the same, I would ask that my solution be reviewed. Regards

[allada]

Thanks, but it looks like this PR is going to likely be accepted:
#1489

[aaronmondal]

Fixed by #1489