Retrofit {Hex,Decimal}NumberExpression from v2 into v0/v1 spec (#657)

Part of #652 

Split out of #650

crates/solidity/inputs/language/definition/05-expressions/04-numbers/productions.yml

@@ -1,23 +1,32 @@
 # yaml-language-server: $schema=../../../generated/productions.schema.json
 
 - name: "NumericExpression"
+  kind: "Parser"
+  inlined: true
+  unversioned:
+    choice:
+      - reference: "DecimalNumberExpression"
+      - reference: "HexNumberExpression"
+
+- name: "DecimalNumberExpression"
+  kind: "Parser"
+  unversioned:
+    sequence:
+      - reference: "DecimalLiteral"
+      - optional:
+          reference: "NumberUnit"
+
+- name: "HexNumberExpression"
   kind: "Parser"
   versioned:
     0.4.11:
       sequence:
-        - choice:
-            - reference: "HexLiteral"
-            - reference: "DecimalLiteral"
+        - reference: "HexLiteral"
         - optional:
             reference: "NumberUnit"
     0.5.0:
-      # "HexLiteral" no longer allows a "NumberUnit"
-      choice:
-        - reference: "HexLiteral"
-        - sequence:
-            - reference: "DecimalLiteral"
-            - optional:
-                reference: "NumberUnit"
+      # Removed optional "NumberUnit"
+      reference: "HexLiteral"
 
 - name: "HexLiteral"
   kind: "Scanner"

crates/solidity/inputs/language/src/dsl.rs

@@ -424,10 +424,10 @@ slang_grammar! {
             { removed in "0.7.0"     (FinneyKeyword | SzaboKeyword) }
         ) ;
 
-        parser NumericExpression = (
-            (HexLiteral { removed in "0.5.0" (NumberUnit ?) }) |
-            (DecimalLiteral (NumberUnit ?))
-        ) ;
+        inline parser NumericExpression = ( DecimalNumberExpression | HexNumberExpression ) ;
+
+        parser DecimalNumberExpression = (DecimalLiteral (NumberUnit ?)) ;
+        parser HexNumberExpression = (HexLiteral { removed in "0.5.0" (NumberUnit ?) }) ;
 
         inline parser OrOperator = BarBar ;