chore: add debug logging for decode errors

[kzantow]

This PR adds debug logging for decode errors. If a file fails to decode, at least a user is now able to run syft -vv to see why all the formats failed, like this:

[0000] DEBUG format syft-6-json returned err: unable to decode: invalid character 'S' looking for beginning of value
[0000] DEBUG format cyclonedx-1-xml returned err: EOF
[0000] DEBUG format cyclonedx-1-json returned err: invalid character 'S' looking for beginning of value
[0000] DEBUG format spdx-2-tag-value returned err: unable to decode spdx-tag-value: got unknown checksum type sha256
[0000] DEBUG format spdx-2-json returned err: unable to decode spdx-json: invalid character 'S' looking for beginning of value
2022/11/19 09:34:55 error during command execution: failed to decode SBOM: unable to identify format

Provides a stop-gap solution for: #1351