Also check "data" provisioning scripts for param usage

[jandubois]

Fixes:

❯ cat test.tmpl
images: [{location: foo.raw}]
provision:
- mode: data
  path: /etc/foo
  content: |
    FOO={{.Param.FOO}}
param:
  FOO: bar

❯ limactl tmpl copy --fill test.tmpl -
FATA[0000] field `param` key "FOO" is not used in any provision, probe, copyToHost, or portForward

With this PR:

❯ limactl tmpl copy --fill test.tmpl - | yq '.provision[0].content'
FOO=bar

[AkihiroSuda]

Thanks

Eventually we should have a test suite for this