Streamline Data Feed Architecture

[jaredbroad]

Expected Behavior

The data feed classes should be 99% identical with small differences at the bottom of the stack depending on the data subscription source.

Actual Behavior

Maintenance and support for data feeds are increasingly difficult due to the current data feed abstractions.

Potential Solution

Refactor the data feed to share the subscription management and data synchronization logic.

Checklist

• I have completely filled out this template
• I have confirmed that this issue exists on the current master branch
• I have confirmed that this is not a duplicate issue by searching issues

[Martin-Molinero]

This has already been implemented through multiple PRs. Detailed information at https://github.com/QuantConnect/Lean/projects/5