R1:73253489bf00

Make src/infrastructure/javelin/markup.php phabricator_form PHP 8.1 compliant

Summary:
src/infrastructure/javelin/markup.php phabricator_form() performs a strcasecmp() operation on an optional attribute withoiut checking to see if it exists first. This causes an 'Passing null to parameter #1 ($string1) of type string is deprecated' error.

Because we subsequenly check to see that the value equals /POST/i, all we need to do is check that the value has some 'true' value before doing the strcasecmp(). If…