fix: strip pseudo inline placeholder from string/heredoc/nowdoc output

[Dextheking1]

Fixes #2087

parser.mjs injects ___PSEUDO_INLINE_PLACEHOLDER___ into the source text for top-level ?>\n<? sequences (workaround for glayzzle/php-parser#170). When a heredoc, nowdoc, or string literal happened to contain that sequence, the sentinel leaked into the formatted output, corrupting the string contents:

  const liftDataWithInlineRanges = <<<EOD
  <?xml version="1.0" encoding="UTF-8" ?>
- ___PSEUDO_INLINE_PLACEHOLDER___<?oxygen RNGSchema="lift.rng" type="xml"?>
+ <?oxygen RNGSchema="lift.rng" type="xml"?>

The inline printer already stripped the sentinel; the string (plain and encapsed) and nowdoc printers printed node.raw/node.value verbatim, so they now strip it too via a shared PSEUDO_INLINE_PLACEHOLDER constant.

Tests: new tests/heredoc fixture (heredoc, nowdoc, and plain-string cases, placeholder leaked before, gone after); full suite 104 suites / 598 tests green.

[mreiden]

Thanks for this — I've been running it locally and the output is right. One thing you may want to add: the new tests/heredoc fixture fails under AST_COMPARE=1 (yarn test:node with the env var set, as CONTRIBUTING suggests):

- Expected  - 2
+ Received  + 2
  "value": "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>
- ___PSEUDO_INLINE_PLACEHOLDER___<?oxygen RNGSchema=\"lift.rng\" type=\"xml\"?>
- ___PSEUDO_INLINE_PLACEHOLDER___<?blueprint schema=\"lift.rng\"?>
+ <?oxygen RNGSchema=\"lift.rng\" type=\"xml\"?>
+ <?blueprint schema=\"lift.rng\"?>

Not a bug in the fix: the "expected" AST comes from parsing the source after parser.mjs injected the sentinel, so it still contains it, while the reformatted output (correctly) doesn't. Stripping ___PSEUDO_INLINE_PLACEHOLDER___ from string/encapsed/nowdoc values in clean.mjs would make the comparison hold.

[Dextheking1]

Good catch, thanks. Added the strip to clean.mjs for string and nowdoc values (heredoc parts are string nodes, so they are covered too). Verified: AST_COMPARE=1 yarn test:node passes, 102 suites / 1174 tests, and the plain suite is green too (596 tests).