Consider Separate flow for Spans Events

[Litarnus]

Instead of using applyToEvent for every type, we can split them by type.

This would help in a few ways:

• More clarity what each type does and what data it needs
• Prevents that data is accidentally attached to wrong types (e.g. tags on logs)
• We could have different Event types with their own data instead of one big class with the union of all fields
• (theoretical) performance gains by reducing the number of type checks and data copy operations

[linear]

PHP-46