`limactl create`: `--set` cannot be specified multiple times

[AkihiroSuda]

limactl create --set .foo=1 --set .bar=2 ignores foo.

Not a recent regression.
The issue happens with v0.23, as well as with the latest v1.0.6.

Workaround

--set '.foo=1 | .bar=2'

[jandubois]

I can take care of it when I add --set support to limactl tmpl copy, but I don't want to add any more code to the current PR; will do it in a follow-up.