R1:d25d630fe5dd

PHP 8.2: fixes for strlen() not accepting NULL anymore, part 1

Summary:
This change avoids some unnecessary uses of the strlen() function,
actually fixing some deprecation warnings in PHP 8.2.

In short, this is the suggested universal replace:

-if(strlen($v))
+if(phutil_nonempty_string($v))

And, if you know PHP, this is also another adoptable replace, but
only for cases where you are sure that the string "0" is not useful:

-if(strlen($v))
+if($v))

As usual the optimal solution depends…