Document mac CI hardware deployment process

[Keno]

This adds a set of configuration files for MDS
(https://bitbucket.org/twocanoes/macdeploystick)
that can be used to automate setting up new macs
with consistent settings/macOS versions.

[staticfloat]

Okay, so here are my notes:

1. Some of the machines seem to be lacking the repo in ~/src (both aarch64 and x86_64), some of them seem to have it.
2. The machines all seem to have ~/.config, ~/.julia, etc… owned by root.
3. One of the machines seems to have wifi turned on and connected; I’ve disabled that.
4. None of the machines seem to have the SSH key deployed in ~/.ssh/authorized_keys.

[Keno]

I think 1-3 are fixed in the version that's in this PR. 4 should just be a matter of adding an extra script into the directory.

[staticfloat]

For (4) the SSH key is here: https://github.com/JuliaCI/sandboxed-buildkite-agent/blob/main/secrets/ssh_keys/julia_buildbot_rsa.pub

[maleadt]

Couple of notes based on what I encountered after upgrading to macOS 15:

1. Disable power management

Even though we run caffeinate, on macOS 15 I've seen the service getting killed and the device entering sleep as a result. It's probably best to disable power management too:

sudo pmset -a sleep 0

# Prevent display sleep
sudo pmset -a displaysleep 0

# Disable disk sleep
sudo pmset -a disksleep 0

# Prevent idle sleep
sudo pmset -a hibernatemode 0
sudo pmset -a autopoweroff 0
sudo pmset -a standby 0

# Disable power button sleep trigger
sudo pmset -a lidwake 0

2. Homebrew shell env in .zsh_rc

zsh seems like the default now, so the configuration ought to be put there as well.

3. Configure juliaup with LTS channel.