[_fe_analyzer_shared] Add evaluateExpression

This adds a helper method that evaluates an [Expression] based on
the semantics that can be deduced from the syntax.

Change-Id: I1b54ee03c1380d337969671133179aa557702a9b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/392440
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Johnni Winther <[email protected]>

Author: johnniwinther

pkg/_fe_analyzer_shared/analysis_options_no_lints.yaml

@@ -21,3 +21,4 @@ analyzer:
     - test/inference/inferred_variable_types/data/**
     - test/inheritance/data/**
     - test/metadata/data/**
+    - test/metadata/evaluate_data/**