get Cache or Server data ?

I must rewrite translationsCache as a provider so that it is
configurable in a config block and so that:
1) it is an instance / singleton
2) instance can hold a ref to storage key prefix and suffix (this
avoids having to pass it as args in so many methods
----> translationsCacheProvider.setKeyFixes(string prefix, string
suffix);

3) instance can hold a ref to the shouldUpdateCache rule function
----> translationsCacheProvider.setShouldUpdateRule(fn expire);

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