[macros] Add support of `augmented` expression

[sgrekhov]

According to the Augmented libraries specification

Inside a member marked augment, the expression augmented can be used to refer to the original function, getter, setter, or variable initializer.

There is no support of augmented expression now nor in analyzer nor in CFE

Dart SDK version: 3.4.0-edge.03101837d9101c571a1ff617c9dbee0b6cc2e131 (main) (Sat Mar 9 04:14:39 2024 +0000) on "linux_x64"