Cache the current user profile

[kbolashev]

This PR adds caching for the UserAPI.get_user_from_token() function.
This will lead to, e.g, caching of the current user, which will be useful for annotations later :)

[dagshub]

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[simonlsk]

• Let's discuss the security issue and decide.

[guysmoilov]

One the one hand, I don't see a particular security issue since if the user has malicious code running in their process, then yes of course it can grab and steal anything. Do you imagine a more exotic threat scenario?

OTOH, why is this necessary? This caching helps with something frequent?

[kbolashev]

OTOH, why is this necessary? This caching helps with something frequent?

This will help with this PR: #503

In particular at the moment user clicks dp.save() with annotations, I have to get the current user to put into the LS task. Having the current user ID cached saves a round-trip every time they're saving annotations.

I initially threw lru_cache on the current user function, but it doesn't account for cases where the token was changed/they changed the user in the middle somehow, so instead I decided to cache this for all tokens.