[WIP] Add pre-archive-dump-cmd support

Uses changes done in composer/composer#3053 to be able to execute build scripts before archives are generated.

Name of event could be different, for instance "pre-package-archive".
For use see issue link below.

Resolves composer/satis#153

Possible todo:
- [ ] Reconsider event name
- [ ] Somehow add possibility to have per package commands