Review suggested PHP's extensions

[lens0021]

• Install wikidiff2 #740
• Use LuaSandbox #857
• Install ext-qmp #863

https://github.com/wikimedia/mediawiki/blob/c6769617430673f9e14da2154c0805963dd8179e/composer.json#L106-L125

Module	Description	Installed
ext-apcu	Local data cache for greatly improved performance	✓
ext-curl	Improved http communication abilities	✓
ext-gd	Support for Graphics Draw
ext-gmp	Support for arbitrary-length integers
ext-intl	ICU integration	✓
ext-mysqli	Allows MediaWiki to use MySQL/MariaDB as a database	✓
ext-openssl	Cryptographical functions	✓
ext-pdo	Allows MediaWiki to use SQLite as a database	✓
ext-pgsql	Allows MediaWiki to use PostgreSQL as a database
ext-posix	Process control	✓
ext-pcntl	Process control
ext-readline	Improved command line support	✓
ext-sockets	Socket support	✓
ext-wikidiff2	Diff accelerator	✓
ext-yaml	Improved YAML parsing performance
ext-zlib	gzip compressiion	✓
monolog/monolog	Flexible debug logging system
nmred/kafka-php	Send debug log events to kafka