Add tests for --package-only CLI option

Signed-off-by: Ayan Sinha Mahapatra <ayansmahapatra@gmail.com>

Author: AyanSinhaMahapatra

tests/packagedcode/data/build_gradle/end2end/build.gradle-package-only-expected.json

@@ -0,0 +1,97 @@
+{
+  "packages": [],
+  "dependencies": [],
+  "files": [
+    {
+      "path": "build.gradle",
+      "type": "file",
+      "package_data": [
+        {
+          "type": "maven",
+          "namespace": null,
+          "name": null,
+          "version": null,
+          "qualifiers": {},
+          "subpath": null,
+          "primary_language": null,
+          "description": null,
+          "release_date": null,
+          "parties": [],
+          "keywords": [],
+          "homepage_url": null,
+          "download_url": null,
+          "size": null,
+          "sha1": null,
+          "md5": null,
+          "sha256": null,
+          "sha512": null,
+          "bug_tracking_url": null,
+          "code_view_url": null,
+          "vcs_url": null,
+          "copyright": null,
+          "holder": null,
+          "declared_license_expression": null,
+          "declared_license_expression_spdx": null,
+          "license_detections": [],
+          "other_license_expression": null,
+          "other_license_expression_spdx": null,
+          "other_license_detections": [],
+          "extracted_license_statement": null,
+          "notice_text": null,
+          "source_packages": [],
+          "file_references": [],
+          "extra_data": {},
+          "dependencies": [
+            {
+              "purl": "pkg:maven/com.google/guava@1.0",
+              "extracted_requirement": "1.0",
+              "scope": "api",
+              "is_runtime": true,
+              "is_optional": false,
+              "is_resolved": true,
+              "resolved_package": {},
+              "extra_data": {}
+            },
+            {
+              "purl": "pkg:maven/org.apache/commons@1.0",
+              "extracted_requirement": "1.0",
+              "scope": "usageDependencies",
+              "is_runtime": true,
+              "is_optional": false,
+              "is_resolved": true,
+              "resolved_package": {},
+              "extra_data": {}
+            },
+            {
+              "purl": "pkg:maven/org.jacoco.ant@0.7.4.201502262128",
+              "extracted_requirement": "0.7.4.201502262128",
+              "scope": "",
+              "is_runtime": true,
+              "is_optional": false,
+              "is_resolved": true,
+              "resolved_package": {},
+              "extra_data": {}
+            },
+            {
+              "purl": "pkg:maven/org.jacoco.agent@0.7.4.201502262128",
+              "extracted_requirement": "0.7.4.201502262128",
+              "scope": "",
+              "is_runtime": true,
+              "is_optional": false,
+              "is_resolved": true,
+              "resolved_package": {},
+              "extra_data": {}
+            }
+          ],
+          "repository_homepage_url": null,
+          "repository_download_url": null,
+          "api_data_url": null,
+          "datasource_id": "build_gradle",
+          "purl": null
+        }
+      ],
+      "for_packages": [],
+      "scan_errors": []
+    }
+  ]
+}