PHP 8.1 | NewFunctions: handle new array_is_list() function

Includes unit test.

Refs:

• https://www.php.net/manual/en/migration81.new-functions.php#migration81.new-functions.core
• https://wiki.php.net/rfc/is_list

PHP 8.1 | NewFunctions: handle new fsync() functions

Includes unit tests.

Refs:

• https://www.php.net/manual/en/migration81.new-functions.php#migration81.new-functions.standard
• https://wiki.php.net/rfc/fsync_function

PHP 8.1 | NewFunctions: handle new image*avif() functions

GD:

• Avif support is now available through the imagecreatefromavif() and
  imageavif() functions, if libgd has been built with avif support.

Includes unit tests.

Refs:

• https://github.com/php/php-src/blob/f67986a9218f4889d9352a87c29337a5b6eaa4bd/UPGRADING#L245-L247
• Propagate AVIF support from libgd php/php-src#7026
• php/php-src@81f6d36

PHP 8.1 | NewFunctions: handle new MySqli function

While only the method is mentioned in the RFC and the Migration guide, a procedural version of the same was also implemented.

Includes unit tests.

Refs:

• https://www.php.net/manual/en/migration81.new-features.php#migration81.new-features.mysqli.mysqli_fetch_column
• https://wiki.php.net/rfc/mysqli_fetch_column
• Implement mysqli_fetch_column php/php-src#6798
• php/php-src@54222a6

PHP 8.1 | NewFunctions: handle new pcntl_rfork() function

Includes unit tests.

Refs:

• https://www.php.net/manual/en/migration81.new-functions.php#migration81.new-functions.pcntl
• Adding pcntl_rfork. php/php-src#3821
• php/php-src@28382aa

PHP 8.1 | NewFunctions: handle new Sodium functions

Includes unit tests.

Refs:

• https://www.php.net/manual/en/migration81.new-functions.php#migration81.new-functions.sodium
• Add crypto_stream_xchacha20 to ext/sodium php/php-src#6868
• php/php-src@f7f1f7f
• Expose libsodium's Ristretto255 API php/php-src#6922
• php/php-src@9b794f8

Related to #1299