Expose RPM signature information (for RPM DB and RPM archives) (#3179)

* feat: expose rpm signature information

This helps with more confident identification of an rpm.

In theory, two rpms can be built that have the same purl string, and
otherwise look identical in syft's output, but the PGP information
would distinguish them as signed either by different keys, or signed at
different times.

In practice, this usually makes no difference since rpms tend to have
unique name/version/release strings. This just gives increased
confidence about the identity of the rpm found in the db.

Signed-off-by: Ralph Bean <rbean@redhat.com>

* chore: generate json schema

Signed-off-by: Ralph Bean <rbean@redhat.com>

* re-generate json schema

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* rename to a more generic signature field

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* rename rpm.pgp to rpm.signatures

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* split out signature fields

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* bump json schema

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* include RPM archives

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* update json schema

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* dont fail on unknown signature type

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

---------

Signed-off-by: Ralph Bean <rbean@redhat.com>
Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>
Co-authored-by: Alex Goodman <wagoodman@users.noreply.github.com>

internal/constants.go

@@ -3,5 +3,5 @@ package internal
 const (
 	// JSONSchemaVersion is the current schema version output by the JSON encoder
 	// This is roughly following the "SchemaVer" guidelines for versioning the JSON schema. Please see schema/json/README.md for details on how to increment.
-	JSONSchemaVersion = "16.0.32"
+	JSONSchemaVersion = "16.0.33"
 )