Support ai.backend.accelerators image label's * value

[yomybaby]

Currently, the session launcher uses the resource limit information of the selected image to display the types of accelerators available for selection. We need to change this logic to use the supported_accelerators information instead.

• If the supported_accelerators value is \*, allow all accelerators provided by the resource group to be selectable.

• Display a warning message: "The currently selected image does not guarantee the operation of the accelerator." when supported_accelerators is \*.

[ironAiken2]

Due to company move, I'm currently experiencing a firewall error (connect: no route to host), so I'll work on this after company move. @yomybaby