[mypyc] Include more operations in the trace log

[JukkaL]

Add these operations to the trace log (note that trace logging is disabled by default):

• Native attribute get/set
• Boxing and unboxing
• Casts
• Incref/decref (including some implicit increfs)

All of these are common operations and can be performance bottlenecks. There are ways to avoid or speed up most of these (possibly through new mypyc features). For example, incref/decref can sometimes be avoided by using borrowing.