feat: make requestUnregisteredTokens concurrent

[alexruzenhack]

Motivation

The user needs the data as quick as possible in a new nano contract request. To achieve this requirement we can make the http request concurrent, however we should respect the rate-limit rules set in public node endpoints.

Acceptance Criteria

• Make requestUnregisteredTokens to call token details in "parallel"
• Add an action to end the request unregistered tokens process
• Add an utility function to split a list in groups

Future possibility

We can implement a client object that implements a more sophisticated limit-rate strategy that adapts to back pressure from server. This control is interesting to pursuit in order to better rationalize the resources at app disposal and at the same time helps the server to heal in case of spike usage.

Note

It closes #531.

Warning

To work properly it depends on the fix on promise leak, see HathorNetwork/hathor-wallet-lib#772.

Security Checklist

• Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.