Introduce a scripts hook

[theofidry]

A few notes from conversations with ondrej;

script idea:

"dump-autoload": [
    "@composer config autoloader-suffix @prefix", <- `@composer` points to whatever Composer binary Box uses
                                                  <- `@prefix` points to the PHP-Scoper prefix; would throw na error if none found
    "@composer config autoloader-suffix @{prefix}CheckSum", <- Example where you use `@prefix` concatenated with another string
    "@composer config platform.php --unset",
    "@composer dump-autoload --classmap-authoritative", <- just rolling your own dump-autoload
    "@box-dump-autoload", <- using the Box default dump-autoload
],

PHPStan changes the composer.json in multiple places:

• https://github.com/phpstan/phpstan-src/blob/dbb8c4bd12cc0863dc85a5ac3435478a67cb9006/compiler/src/Console/PrepareCommand.php#L61-L78
• And then I manipulate autoloader-suffix in phar.yml
  20:21
  But that’s only to produce a reproducible PHAR file, to compare checksums and to decide whether the PHAR should be commited to phpstan/phpstan or not
  20:21
  For example if only tests change, PHAR checksum doesn’t change.
  20:22
  In reality the PHAR would always change because of different scoper prefix but I compile another PHAR which is reproducible and to compare the checksums.
  20:22
  So I’m not sure if something in Box’s side would make my job easier, probably not