fix: floating promises and fork usage on login saga

[diegolmello]

Proposed changes

Fixes:

• Two floating promises that would keep loginSuccess saga hanging
• Redux-Saga's fork used instead of put

As far as I could tell, there was no visible bug.
takeLatest would cancel the loginSuccess running anyway, while the fork was declared at the top of the saga, so there was enough time to dispatch their own saga.

Issue(s)

How to test or reproduce

• Open simulator with Reactotron connected
• Do a login
• See how LOGIN_SUCCESS saga would never finish (fixed on this PR)

Screenshots

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves a current function)
• New feature (non-breaking change which adds functionality)
• Documentation update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules

Further comments

CORE-91