ControlStructures: add new utility to parse match expressions to its parts

[jrfnl]

A utility to parse PHP 8.0 match expressions into the following parts for each "leaf":

• Condition/comparison values (array as this can be a single value or multiple values)
• Return value

Needs a think about how to handle default, which isn't a condition/comparison value, but does have a return value.

Needs to take match expressions which don't have a trailing comma at the end of the last expression into account.