test: add StageTests.test_zip() to run zip inside a stage too

Similar to the tar test this adds a zip test that runs inside
the stages.

test/data/stages/zip/zip.json

@@ -898,7 +898,7 @@
       ]
     },
     {
-      "name": "zip",
+      "name": "tree",
       "build": "name:build",
       "stages": [
         {
@@ -915,13 +915,7 @@
           "options": {
             "filename": "zipfile.zip"
           }
-        }
-      ]
-    },
-    {
-      "name": "zip-with-paths",
-      "build": "name:build",
-      "stages": [
+        },
         {
           "type": "org.osbuild.zip",
           "inputs": {
@@ -934,7 +928,7 @@
             }
           },
           "options": {
-            "filename": "zipfile.zip",
+            "filename": "zipfile-w-includes.zip",
             "include": [
               "testfile"
             ]

test/data/stages/zip/zip.mpp.yaml

@@ -30,7 +30,7 @@ pipelines:
             - from:
                 mpp-format-string: input://inlinefile/{embedded['42']}
               to: tree:///testfile2
-  - name: zip
+  - name: tree
     build: name:build
     stages:
       - type: org.osbuild.zip
@@ -42,9 +42,7 @@ pipelines:
               - name:input-tree
         options:
           filename: zipfile.zip
-  - name: zip-with-paths
-    build: name:build
-    stages:
+      # one zip with inclues
       - type: org.osbuild.zip
         inputs:
           tree:
@@ -53,5 +51,5 @@ pipelines:
             references:
               - name:input-tree
         options:
-          filename: zipfile.zip
+          filename: zipfile-w-includes.zip
           include: ['testfile']