Fix GH-14481: realpath() and SplFileInfo::getRealPath inside Phar

[iliaal]

realpath() and SplFileInfo::getRealPath() route directly through VCWD_REALPATH, which has no notion of stream wrappers. For a phar:// URL the chain treats the URI as relative, prepends CWD, and stat()s a nonsense path, so existing entries inside a Phar return false even though file_exists() / is_file() / include all see them.

Before VCWD_REALPATH, look up the stream wrapper for the path. If a non-plain, non-URL wrapper supplies url_stat and reports SUCCESS, return the input string; on FAILURE, return false. Plain paths (and file:// URLs that resolve back to the plain-files wrapper) keep the existing VCWD_REALPATH semantics: realpath cache, ZTS access guard, and open_basedir check. For phar URLs, open_basedir is enforced by the wrapper's own url_stat, matching how is_file() and file_exists() behave today.

The !wrapper->is_url guard scopes the new path to local-style wrappers. URL-style wrappers (http://, ftp://, data://, user wrappers registered with STREAM_IS_URL) keep returning false, so realpath() does not gain network or third-party url_stat side effects. In-tree, only phar matches the new branch. User wrappers registered without STREAM_IS_URL that implement url_stat will now have url_stat called from realpath(). PharFileInfo, SplFileObject, DirectoryIterator, RecursiveDirectoryIterator, and FilesystemIterator inherit SplFileInfo::getRealPath and pick up the fix.

stream_resolve_include_path() is intentionally untouched; it is an include-path search that uses the realpath cache, not URL canonicalisation.

Fixes php#14481

[iliaal]

Promoted to upstream: php#21883