Since the version 6.7.4, the "0" is considered like empty string and not displayed

Co-authored-by: William Desportes <[email protected]>

The condition allowed to add ExtGState in all PDF/A modes and disallowed
in default mode.

This fix inlines the condition with setExtGState to allow transparency
parameters for non-PDF/A and PDF/A > 1 documents.

The state condition is copied from 'setExtGState'.

When document is encrypted then /DA string must be encrypted,
without this Acrobat cannot allow fill form fields.

* Try to use random_bytes() first if it's available
* Do not include the server parameters in the generated seed, as
they might contain sensitive data

As all current usages of getRandomSeed() directly hash the seed,
there should be no BC breaking changes.

The main source of entropy is more than enough on its own if
random_bytes() or openssl_random_pseudo_bytes() are available.

…but not other annot on a page

The xml_set_object() function will be deprecated in PHP 8.4 as well as
passing non-callable strings to the xml_set_*_handler() functions.

Instead of using xml_set_object(), the string method names in
xml_set_element_handler() and xml_set_character_data_handler() should be
replaced with callables.

- https://wiki.php.net/rfc/deprecations_php_8_4#xml_set_object_and_xml_set_handler_with_string_method_names

Signed-off-by: Maurício Meneghini Fauth <[email protected]>