archiveloop: don't clean on bootup

Only clean the cam image after successful archiving, to prevent
sentry events being deleted that haven't yet been archived, and
may be lost when snapshots are expired.

setup: workarounds for slow Pi Zero W

Configuring wifi failed on Raspberry Pi Zero W due to Network Manager starting
well after rc-local. Retry configuring wifi for one minute before failing.
Also do a lazy unmount of /mnt/cam after creating the various folders during
setup, to prevent the unmount failing due to the mountpoint being busy.

pi-gen-sources: simplify and update for building bookworm image

setup: remove obsolete windows and macos scripts

Don't delete v7+, it's needed for RpiZero2W

Don't delete v7+ modules, needed for Raspberry Pi Zero 2 W.
Add sntp, and use it to set the time before setup, to avoid problems
with certs being invalid.
Update for default cmdline changes.

Update prebuilt image

Add additional packages to the prebuilt image to save time during setup.
Increase root partition size to allow for easier updates after setup.
Update build instructions.

Update sample config

Condense overly verbose discussion of disk sizes, add a note
regarding the new 32GB minimum size warning that appeared in Tesla
software version 2020.48.10, and various minor corrections.

Update OneStepSetup.md

Stretch release is no more, so don't mention it in the setup doc.

Ignore fstrim failure during setup

Use automount to mount snapshots

This significantly improves startup time when many
snapshots are present.