[Intelligent code completion] Suggest object attributes when using paginate

[Poitrin]

Describe the bug / Actual
👍 Global objects used with paginate are suggested …

👎 … but attributes of a specific object are not suggested.

Expected
Attributes of specific objects (e.g. customer.orders) should be suggested too.

Debugging information

• OS: macOS
• Version: 1.12.0

Additional context
Liquid::Template.parse(markup) in VariableLookupFinder will raise an error, as it doesn't know paginate.
This problem could be solved with TolerantParser::Template.parse(markup).
However, the resulting tag is much "lighter" and might not contain all the relevant information.

In the screenshot, you see the debug output of paginate customer.orders vs. echo customer.orders.

Outsourced from #683