feat(Provenance): Add DirectoryProvenance as a LocalProvenance

In contrast to the previously added `RemoteProvenance` stands the
`LocalProvenance`, which has no remote source, but instead references
a local input of some kind.
The `DirectoryProvenance` references a local project directory,
which is lacking supported (remote) version control.
It is defined by its local directory path only.

See [1] for more context on the new Provenance Hierarchy.

[1]: oss-review-toolkit#8803 (comment)

Signed-off-by: Jens Keim <jens.keim@forvia.com>

model/src/main/kotlin/Provenance.kt

@@ -19,6 +19,8 @@
 
 package org.ossreviewtoolkit.model
 
+import java.nio.file.Files
+import java.nio.file.Path
 import com.fasterxml.jackson.core.JsonParser
 import com.fasterxml.jackson.databind.DeserializationContext
 import com.fasterxml.jackson.databind.JsonNode
@@ -45,6 +47,8 @@ sealed interface KnownProvenance : Provenance
 
 sealed interface RemoteProvenance : KnownProvenance
 
+sealed interface LocalProvenance : KnownProvenance
+
 /**
  * Provenance information for a source artifact.
  */
@@ -83,6 +87,23 @@ data class RepositoryProvenance(
     override fun matches(pkg: Package): Boolean = vcsInfo == pkg.vcsProcessed
 }
 
+/**
+ * Provenance information for a local directory path.
+ */
+data class DirectoryProvenance(
+    val directoryPath: Path
+) : LocalProvenance {
+    init {
+        require(Files.exists(directoryPath)) { "The directory path must exist." }
+    }
+
+    /**
+     * Return true if this provenance's directoryPath matches the package URL of the [package][pkg],
+     * as it contains the local file path for non-remote Provenances.
+     */
+    override fun matches(pkg: Package): Boolean = directoryPath.toString() == pkg.purl
+}
+
 /**
  * A custom deserializer for polymorphic deserialization of [Provenance] without requiring type information.
  */