Fix CRLF handling in external scanner

- Consume \r as part of token instead of skipping it
- Break after consuming \n to avoid processing multiple lines
- Consume leading whitespace separately for indent calculation
- Fix ASCII_CONTENT to return false at EOF without asciiend

This fixes ERROR tokens with CRLF line endings, especially
with trailing blank lines.

src/node-types.json

@@ -1543,7 +1543,6 @@
   {
     "type": "source_file",
     "named": true,
-    "root": true,
     "fields": {},
     "children": {
       "multiple": true,
@@ -2054,8 +2053,7 @@
   },
   {
     "type": "block_comment",
-    "named": true,
-    "extra": true
+    "named": true
   },
   {
     "type": "break_statement",
@@ -2067,8 +2065,7 @@
   },
   {
     "type": "comment",
-    "named": true,
-    "extra": true
+    "named": true
   },
   {
     "type": "continue_statement",