Disable dim, blanking, & sleep during install

### Problem

During a recent install my laptop was so slow that the filesystem copy stage took over 2 hours & at one point I had walked away for so long that it had gone to sleep & stopped entirely, requiring keyboard input to get started again. This could have cost a lot of time had I left it to churn overnight.

### Proposal

Just reconfigure power management so everything stays on all the time, probably even if the lid gets closed by accident.

### Prior Art (Optional)

_No response_