grammar,compiler: Add Support For Fixed-Width Integers

Distinguishing between signed and unsigned fixed-width integer
types must still be done.

Signed-off-by: Will Hawkins <hawkinsw@obs.cr>

Tests/p4rseTests/ExpressionTests/FunctionCall.swift

@@ -182,5 +182,5 @@ import TreeSitterP4
 
   let error = try #UseErrorResult(Program.Compile(simple_parser_declaration))
 
-  #expect(error.msg().contains("{29, 12}: Type of expression in return statement (Boolean) is not compatible with function return type (Int)"))
+  #expect(error.msg().contains("{29, 12}: Type of expression in return statement (Boolean) is not compatible with function return type (Int (width: Infinite))"))
 }

Tests/p4rseTests/ExpressionTests/SelectExpression.swift

@@ -132,7 +132,7 @@ import TreeSitterP4
     #RequireErrorResult(
       Error(
         withMessage:
-        "Error(s) parsing select cases: {81, 4}: Key expression of type Boolean is not compatible with selector type Int"
+        "Error(s) parsing select cases: {81, 4}: Key expression of type Boolean is not compatible with selector type Int (width: Infinite)"
       ),
       Program.Compile(simple_parser_declaration)))
 }