Support for kernel arguments for initial agent boot for different platforms

[frezbo]

When booting a bunch of machines with Sidero, for example

• Dell Servers - console=tty0 console=ttyS1,115200n8
• Raspberry Pi - console=tty0 console=ttyAMA0,115200
• RockPi4 - console=tty0 console=ttyS2,1500000n8

each of the platform expect a different kernel argument to set the serial console

Currently Sidero only supports setting agent boot args via SIDERO_CONTROLLER_MANAGER_EXTRA_AGENT_KERNEL_ARGS

This makes it harder as a user to view console logs over serial for different platforms, as a workaround I manually edit the sidero controller deployment before booting each platform to be able to gather the serial logs

While I don't see any easy way to figure this out, this is definitely a UX issue

Maybe the tftp/pxe sends some board specific info? :shrug: