Go 1.19 started reformatting code in a way that makes it more obvious
how it will be rendered on pkg.go.dev. It gets it almost right, but not
entirely. Therefore, I had to modify some of the comments so that they
are formatted correctly.
These two passes are related, but can definitely work independently.
Which is what this change does: it splits the two passes. This should
make it easier to change these two new passes in the future.
This change now also enables slightly better testing by testing these
two passes independently. In particular, the reflect lowering pass got
some actual tests: it was barely unit-tested before.
I have verified that this doesn't really change code size, at least not
on the microbit target. Two tests do change, but in a very minor way
(and in opposite direction).
