allow numeric users and groups

Previously, users and groups were set to only allow alphabetical first
characters.

corpus/user.txt

@@ -23,4 +23,15 @@ USER foo:bar
 		user: (unquoted_string)
 		group: (unquoted_string)))
 		
+==================
+Numerical
+==================
 
+USER 1004:1004
+
+---
+
+(source_file
+	(user_instruction
+		user: (unquoted_string)
+		group: (unquoted_string)))

grammar.js

@@ -112,7 +112,7 @@ module.exports = grammar({
       ),
 
     _user_name_or_group: ($) =>
-      repeat1(choice(/[a-z][-a-z0-9_]*/, $.expansion)),
+      repeat1(choice(/([a-z][-a-z0-9_]*|[0-9]+)/, $.expansion)),
 
     workdir_instruction: ($) =>
       seq(alias(/[wW][oO][rR][kK][dD][iI][rR]/, "WORKDIR"), $.path),

src/grammar.json

@@ -541,7 +541,7 @@
         "members": [
           {
             "type": "PATTERN",
-            "value": "[a-z][-a-z0-9_]*"
+            "value": "([a-z][-a-z0-9_]*|[0-9]+)"
           },
           {
             "type": "SYMBOL",

src/tree_sitter/parser.h

@@ -123,6 +123,7 @@ struct TSLanguage {
     unsigned (*serialize)(void *, char *);
     void (*deserialize)(void *, const char *, unsigned);
   } external_scanner;
+  const TSStateId *primary_state_ids;
 };
 
 /*