* Parse *= separately in types
Previously, when the scanner produced `*=` as a single token, the type
parser ran special-case code to produce an "optional all type", which
only makes sense when the `=` really should be attached to the `*`. This
is often not the case.
The correct solution, which I missed when I first wrote this code, is to
have the scanner go back and produce a separate `=` token, which is what
this PR does.
* add test from #38551
* we ❤️ semicolons