Prepare to changes to var in AST

After https://bugs.openjdk.org/browse/JDK-8268850, `VariableTree#getType` returns a new AST node `VarTypeTree` for variables declared with `var`.

The new node could be handled in the visitor by implementing `visitVarType`, but that API is only available on the latest JDK versions using var, which would require creating a new version-specific visitor implementation. To defer doing that, this fix re-orders the logic that handles variable types to check if the next token is `var` first, to avoid needing to handle the new AST node.

PiperOrigin-RevId: 876244813

Author: cushon

core/src/main/java/com/google/googlejavaformat/java/JavaInputAstVisitor.java

@@ -3686,15 +3686,15 @@ protected int declareOne(
           builder.open(ZERO);
           {
             visitAnnotations(annotations, BreakOrNot.NO, BreakOrNot.YES);
-            if (typeWithDims.isPresent() && typeWithDims.get().node != null) {
+            if (isVar) {
+              token("var");
+            } else if (typeWithDims.isPresent() && typeWithDims.get().node != null) {
               scan(typeWithDims.get().node, null);
               int totalDims = dims.size();
               builder.open(plusFour);
               maybeAddDims(dims);
               builder.close();
               baseDims = totalDims - dims.size();
-            } else if (isVar) {
-              token("var");
             } else {
               scan(type, null);
             }