PHP 7.3 compatibility - Remove AES Encryption compatibility module (7.x-1.x)

This is a port to 1.x of issue #2925453: Remove AES Encryption compatibility module →

Running phpcs returns the below errors:

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FOUND 13 ERRORS AFFECTING 7 LINES
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 212 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since
     |       | PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available
     |       | instead
 212 | ERROR | The constant "MCRYPT_MODE_CBC" is deprecated since PHP 7.1 and
     |       | removed since PHP 7.2
 213 | ERROR | Function mcrypt_enc_get_key_size() is deprecated since PHP 7.1
     |       | and removed since PHP 7.2; Use OpenSSL instead
 213 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since
     |       | PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available
     |       | instead
 228 | ERROR | Function mcrypt_generic_init() is deprecated since PHP 7.1 and
     |       | removed since PHP 7.2; Use OpenSSL instead
 228 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since
     |       | PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available
     |       | instead
 229 | ERROR | Function mdecrypt_generic() is deprecated since PHP 7.1 and
     |       | removed since PHP 7.2; Use OpenSSL instead
 230 | ERROR | Function mcrypt_generic_deinit() is deprecated since PHP 7.1 and
     |       | removed since PHP 7.2; Use OpenSSL instead
 230 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since
     |       | PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available
     |       | instead
 232 | ERROR | Function mcrypt_module_close() is deprecated since PHP 7.1 and
     |       | removed since PHP 7.2; Use OpenSSL instead
 232 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since
     |       | PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available
     |       | instead
 293 | ERROR | Function mcrypt_module_open() is deprecated since PHP 7.1 and
     |       | removed since PHP 7.2; Use OpenSSL instead
 293 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since
     |       | PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available
     |       | instead
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