Model optional overlay annotations

Preserve the anonymous question-mark suffix in annotation arguments so overlay[caller?] and overlay[local?] use their dedicated AST classes. Add regression coverage for optional and non-optional overlay annotations.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: owen-mc

ql/ql/src/codeql_ql/ast/Ast.qll

@@ -2530,13 +2530,25 @@ private class AnnotationArg extends TAnnotationArg, AstNode {
 
   AnnotationArg() { this = TAnnotationArg(arg) }
 
+  private predicate isOptional() {
+    arg.getLocation().getEndLine() != arg.getChild().getLocation().getEndLine()
+    or
+    arg.getLocation().getEndColumn() != arg.getChild().getLocation().getEndColumn()
+  }
+
   /** Gets the name of this argument. */
   string getValue() {
-    result =
-      [
-        arg.getChild().(QL::SimpleId).getValue(), arg.getChild().(QL::Result).getValue(),
-        arg.getChild().(QL::This).getValue()
-      ]
+    exists(string value |
+      value =
+        [
+          arg.getChild().(QL::SimpleId).getValue(), arg.getChild().(QL::Result).getValue(),
+          arg.getChild().(QL::This).getValue()
+        ]
+    |
+      result = value and not this.isOptional()
+      or
+      result = value + "?" and this.isOptional()
+    )
   }
 
   override string toString() { result = this.getValue() }

ql/ql/test/queries/overlay/InlineOverlayCaller/OverlayAnnotations.expected

@@ -0,0 +1,3 @@
+| Test.qll:1:1:1:15 | overlay[local?] | overlay[local?] |
+| Test.qll:9:1:9:15 | overlay[caller] | overlay[caller] |
+| Test.qll:16:1:16:16 | overlay[caller?] | overlay[caller?] |

ql/ql/test/queries/overlay/InlineOverlayCaller/OverlayAnnotations.ql

@@ -0,0 +1,9 @@
+import ql
+
+from Annotation a
+where
+  a instanceof OverlayCaller or
+  a instanceof OverlayCallerQ or
+  a instanceof OverlayLocal or
+  a instanceof OverlayLocalQ
+select a, a.toString()