feat:[#358] add custom reboot and close commands

[jardon]

• add recipe keys for reboot and close commands
• call custom commands with subprocess instead hardcoded commands
• add recipe keys to example

closes #358

[mirkobrombin]

Just to clarify, in vanilla os there is no need to reboot anymore, we’ll have to update our reboot command (here or in the desktop image) to simply logout the user.

[jardon]

We use the reboot_condition set to "false" to avoid the reboot. so even with setting the recipe reboot command, it wont get triggered unless we change the reboot condition.

[jardon]

@mirkobrombin why do we layer a recipe in instead of using the one in the repo? we include that one as well as an example in the repo. the included one and the one here are the same except for the reboot condition

[jardon]

the answer is that we dont. this should be more than okay to merge as is. we could change the reboot command in our recipe to the logout command, but that doesnt do anything as our reboot condition always allows us to log out. this change is really introduced for use outside of vanilla to make our tooling more flexible.