Grype should support all inputs as syft does

[wagoodman]

It seems that grype is not behaving as syft does when passing individual files that are not sboms:

❯ syft -o json conan.lock > /tmp/sbom
 ✔ Indexed file system                                                                                                                                                              /Users/wagoodman/Downloads
 ✔ Cataloged contents                                                                                                                         85cd69f3c5c005fcd8d7e7210d9a50ea8fe9768e2b9dda0440c525350af9dd7e
   ├── ✔ Packages                        [1 packages]
   └── ✔ Executables                     [0 executables]

❯ grype /tmp/sbom
 ✔ Vulnerability DB                [no update available]
 ✔ Scanned for vulnerabilities     [0 vulnerability matches]
   ├── by severity: 0 critical, 0 high, 0 medium, 0 low, 0 negligible
   └── by status:   0 fixed, 0 not-fixed, 0 ignored
No vulnerabilities found

❯ grype conan.lock
 ✔ Vulnerability DB                [no update available]
failed to catalog: unable to decode sbom: sbom format not recognized

Expected behavior is for the conan.lock to be cataloged by syft then scanned by grype.