Output configuration

[inclement]

Vivarium needs config options (accessible via viv_config.h and config.toml) for configuring output rotation, dpi etc.

[inclement]

Maybe we should just support the wlr-output-management protocol and let users use https://github.com/emersion/kanshi or equivalent, but having a simple Vivarium-specific config seems appealing too. Adding the protocol support is important though.

[genesistms]

Is there a way to configure it for now?

[inclement]

@genesistms #79 implements this feature and appears to work, but likely has bugs (including at least one reported on the ticket). It will be merged once I get some hardware to test properly with, or if someone else can pick it up and vouch for it.