This change will vendor the new version of the exoscale-import
post-processor component, but remove all of its code from Packer. After
the v1.8.0 release this change should be removed entirely.

This vendor process is being used as a workaround for decoupling the
exoscale-import component without causing a breaking change in Packer.

Users of Exoscale are encouraged to leverage `packer init` for
installing the latest version of packer-plugin-exoscale.