Create "direct" install sub command that will be called in a posttrans on package mode installations #927
Description
As part of https://fedoraproject.org/wiki/Changes/BootLoaderUpdatesPhase1, for package mode installations, we will update the bootloader (copy from /usr to boot or ESP) as part of the posttrans scriptlet.
This is a slightly different path as the current update path where we have the systemd-run logic, and we notably don't have any prepared metadata.
We can start by creating a command that does a simple copy (like the scripts do) and then iterate on merging the logic between the package mode and the image mode use case.
See change and current sample/basic installation scripts:
- https://fedoraproject.org/wiki/Changes/BootLoaderUpdatesPhase1
- https://src.fedoraproject.org/rpms/grub2/pull-request/136
- https://src.fedoraproject.org/rpms/shim/pull-request/4
See related issue: #926