impl clone for iter/values/keys of storage types

[g4titanx]

issue no: #1121

[frol]

CI still fails, by the way

[frol]

@g4titanx Please also add the test from the original issue to demonstrate the cycle() now works as expected.

[frol]

@g4titanx Could you, please, address the CI errors?

[g4titanx]

@g4titanx Could you, please, address the CI errors?

done, checks successful

[frol]

Short and sweet!

@g4titanx Thank you for contributing to NEAR ecosystem!

@race-of-sloths score 3

[race-of-sloths]

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