Doesn't recognize `--unpack` argument to `ADD`

[fastcat]

Example:

# syntax=docker/dockerfile:1
FROM debian
ADD --unpack \
	https://github.com/asdf-vm/asdf/releases/download/v0.18.0/asdf-v0.18.0-linux-amd64.tar.gz \
	/usr/local/bin/

Gives red squiggles on the --unpack arg, even though it is valid so long as the # syntax=... directive is present.

The suggested fix to change it to --chown is particularly unhelpful 🙃

VSCode: 1.105.1
Extension version: 2.3.0

[bwateratmsft]

/cc @rcjsuen

[rcjsuen]

Thank you for raising this issue. I have opened rcjsuen/dockerfile-utils#131 to track this.

As a workaround, you can ignore this by adding # dockerfile-utils: ignore to the line before the ADD although I recognize the situation is not ideal.

# syntax=docker/dockerfile:1
FROM debian
# dockerfile-utils: ignore
ADD --unpack \
	https://github.com/asdf-vm/asdf/releases/download/v0.18.0/asdf-v0.18.0-linux-amd64.tar.gz \
	/usr/local/bin/