Use builder by default and fail if --no-container and unsupported platform

[ptrus]

Fixes: #652

TODO:

• actually maybe do as suggested in oasis rofl build without builder should just fail on macOS #652 (comment)
• update quickstart docs to not recommend docker run --platform linux/amd64 --volume .:/src -it ghcr.io/oasisprotocol/rofl-dev:main oasis rofl build anymore, once this is released

oasis rofl build should now just work on all platforms.

Behaviour is something like:

Host/arch	Manifest builder	Flag	Docker/podman available?	Result
linux/amd64	none	none	n/a	Native build
linux/amd64	set	none	yes	Container build (manifest image)
linux/amd64	set	none	no	Error: builder specified but no docker/podman
linux/amd64	any	--no-container	n/a	Native build (flag overrides)
non-linux/other arch	any	--no-container	any	Error: native builds only on linux/amd64; remove --no-container
non-linux/other arch	any	none	yes	Container build (manifest image if set, else default)
non-linux/other arch	any	none	no	Error: native builds only on linux/amd64 and no docker/podman available

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