FR: Control logging behaviour

### What are you trying to do?

For embedded devices especially, it would be useful to be able to avoid logging to disk, and to log to a ramdisk before uploading or disable local logging completely (acknowledging that there will be no available support for this scenario).

`--no-logs-no-support` will still log locally, which can fill up storage on an embedded device, and the procedure to redirect logs to /dev/null per process is different across distributions.

### How should we solve this?

Add a `tailscaled` flag to control log behaviour, or accept an entry in /etc/default/tailscaled

Suggested options
`RAM` - create a RAMdisk and log to there, continuing to upload to the telemetry server
`NONE` - Disable local logging
`FILE=xxx` - allow the user to specify logging to a file, rather than through syslog/journalctl - this could then be on a different fs, etc.

### What is the impact of not solving this?

More customization for devices with limited resources.

### Anything else?

_No response_