feat(build): print error on build flag --output=type=something

[iTrooz]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Two things:

• make build flag --output=tar,dest=- have correct behaviour (streaming to stdout)
• print error on build flag --output=type=something instead of outputting image to folder type=something (this is the case whether "something" is a valid type or not)

How to verify it

• Run podman build . --output=tar,dest=-
• Run podman build --output=type=something

Which issue(s) this PR fixes:

None

Special notes for your reviewer:

Does this PR introduce a user-facing change?

make build flag `--output=tar,dest=-` have correct behaviour (streaming to stdout)
print error on build flag `--output=type=INVALID` instead of outputting image to folder `type=INVALID`

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: iTrooz
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[iTrooz]

I updated the title with the most important change. Would you like me to split the PR into 2 instead ?

[packit-as-a-service]

Ephemeral COPR build failed. @containers/packit-build please check.

[packit-as-a-service]

Ephemeral COPR build failed. @containers/packit-build please check.

[packit-as-a-service]

Ephemeral COPR build failed. @containers/packit-build please check.

[iTrooz]

CI failed because of an image pull timeout. TestConformance/header-builtin succeeds locally. I think it should be re-run