Detect invalid metadata exports errors in next-swc (#46077)
* Use next-swc to detect invalid metadata exports
* In client components page under app dir, metadata exports are not
available
* In server components page under app dir, metadata and gM exports can
be exported together
Move sync metadata / async metadata typing resolving test to UT
Closes NEXT-368
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Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>
