* [core] Add format override expression and formatted section to evaluation context
* [core] Add textColor to TaggedString's formatted section
* [core] Add FormatSectionOverrides and introduce overridable properties
* [core] Populate symbol layer paint properties for text sections
* [core] Add benchmark for style that uses text-color override
* [core] Add unit test for FormatOverrideExpression
* [core] Add unit test for FormatSectionOverrides
Issue #10714
- Each expression stores its operator as a string, and default serialization is [operator, serialize(child1), ...]
- Custom implementations of `serialize` for Expression types that don't follow the pattern
- expression::Value -> mbgl::Value converter
- node_expression bindings to expose `serialize`
