[PHP-NOTES] note 130651 added to filter.constants

We can add FILTER_FLAG_EMPTY_STRING_NULL:
<?php
- function filter_sanitize_string(mixed $value, int $flags = 0): string|false {
+ function filter_sanitize_string(mixed $value, int $flags = 0): string|false|null {
+     if ($flags & FILTER_FLAG_EMPTY_STRING_NULL && $value === "") {
+         return null;
+    }
?>

For FILTER_FLAG_STRIP_BACKTICK, there is a bug history
(https://bugs.php.net/bug.php?id=69202)
so I did not attempt to code compatility through version history.
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Probable Submitter: 2604:3d08:5e7b:f300:649d:ed01:f6c5:7ae7
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Manual Page -- https://php.net/manual/en/filter.constants.php
Edit        -- https://main.php.net/note/edit/130651
Del: integrated  -- https://main.php.net/note/delete/130651/integrated
Del: useless     -- https://main.php.net/note/delete/130651/useless
Del: bad code    -- https://main.php.net/note/delete/130651/bad+code
Del: spam        -- https://main.php.net/note/delete/130651/spam
Del: non-english -- https://main.php.net/note/delete/130651/non-english
Del: in docs     -- https://main.php.net/note/delete/130651/in+docs
Del: other reasons-- https://main.php.net/note/delete/130651
Reject      -- https://main.php.net/note/reject/130651
Search      -- https://main.php.net/manage/user-notes.php