[FEATURE] Parse annotations from the SANY comments

[konnov]

As discussed in #162, it should be possible to write type annotations in comments:

VARIABLE
  \* type: Set(Int)
  S

\* type: (Int) => Bool
Mem(e) == \E x \in S: x = e

We should integrate annotations in SanyImporter and propagate them to the type checker.

[konnov]

It is actually a good idea to hide the annotations in comments. Our current approach with extending the Apalache module introduces an additional dependency.

[konnov]

This is implemented in #503.