[cfe] Add FileUriConstantExpression

This adds FileUriConstantExpression, a subclass of ConstantExpression, to support correct file offset of annotations for augmentations and patches.
The FileUriExpression is used to carry the file uri of the expression
before constant evaluation.

TEST=general/patch_annotations

Change-Id: I0dc8a0cb97dd530fd1960785d38c2d5e4883c3dd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/311660
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>

pkg/kernel/binary.md

@@ -147,7 +147,7 @@ type CanonicalName {
 
 type ComponentFile {
   UInt32 magic = 0x90ABCDEF;
-  UInt32 formatVersion = 105;
+  UInt32 formatVersion = 106;
   Byte[10] shortSdkHash;
   List<String> problemsAsJson; // Described in problems.md.
   Library[] libraries;
@@ -1192,6 +1192,14 @@ type ConstantExpression extends Expression {
   ConstantReference constantReference;
 }
 
+type FileUriConstantExpression extends Expression {
+  Byte tag = 108;
+  FileOffset fileOffset;
+  UriReference fileUri;
+  DartType type;
+  ConstantReference constantReference;
+}
+
 abstract type Constant extends Node {
   Byte tag;
 }