This fixes custom attribute syntax highlighting on parameters and functions
(where function builders can be applied). They weren't being walked in
the function position previously and were walked out of source order in the
parameter position.
It also fixes rename of the property wrapper and function builder type
names that can appear in custom attributes, as well as rename of property
wrapper constructors, that can appear after the type names, e.g.
`@Wrapper(initialValue: 10)`. The index now also records these constructor
occurrences, along with implicit occurrences whenever a constructor is
called via default value assignment, e.g. `@Wrapper var foo = 10`, so that
finding calls/references to the constructor includes these locations.
Resolves rdar://problem/49036613
Resolves rdar://problem/50073641
We weren't renaming all occurrences of 'x' in the cases like the below:
case .first(let x), .second(let x):
print("foo \(x)")
fallthrough
case .third(let x):
print("bar \(x)")
We would previously only rename occurrences within the case statement the query
was made in (ignoring fallthroughs) and for cases with multiple patterns (as in
the first case above) we would only rename the occurrence in the first pattern.
