display handlers should be able to output logs

[qweeah]

Display handlers take care of formatting the output. It is possible that the output cannot be formatted, and handler need to output logs without terminating the whole execution.

E.g. when fetching a manifest, the content is successfully fetched but cannot be parsed into expected structure:

oras/cmd/oras/internal/display/metadata/json/manifest_fetch.go

Lines 42 to 44 in 6c5e2cf

	if err := json.Unmarshal(content, &manifest); err != nil {
	manifest = nil
	}

Currently such parsing errors are silently ignored.