feat: Read messages on room close to prevent fetching already seen messages

[diegolmello]

Proposed changes

We are reading for every chunk of messages received, but we're not updating subscription.lastOpen, which is the value used as the "from date" to fetch new messages next time the room is opened.

Issue(s)

How to test or reproduce

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

NATIVE-576