Add --platform argument to devcontainer up

[Duncan Ogilvie (mrexodia)]

I noticed that when running devcontainer up the docker pull does not pass the --platform argument in runArgs correctly:

{
	"name": "x86-boot-sector-c",
	"image": "ghcr.io/mrexodia/x86-real-mode-bootloader:latest",
	"runArgs": ["--platform=linux/amd64"] // Support Rosetta
}

Added a --platform CLI override to devcontainer up and extract the default from runArgs. The CLI argument wins.

[Duncan Ogilvie (mrexodia)]

Abdurrahmaan Iqbal (@abdurriq) Christof Marti (@chrmarti) would it be possible to approve the workflows?