Continued work on access resolution of field access vs self messages.
Now, lexical context is considered for field assignment in literal
dicts.

E.g.

x /*x1*/ = 12
var obj = #[
	x /*x2*/ = x // x is resolved as x1
	y => x // x is resolved as x2
]

Signed-off-by: Jakob Brandsborg Ehmsen <jakobehmsen.github@gmail.com>