Add workflow test for SplitPairedAndUnpairedTool

Test splitting a list:paired_or_unpaired collection with mixed paired
and unpaired elements, verifying both output collections receive the
correct elements.

lib/galaxy_test/workflow/split_paired_and_unpaired.gxwf-tests.yml

@@ -0,0 +1,48 @@
+- doc: |
+    Test splitting a list:paired_or_unpaired collection with mixed paired
+    and unpaired elements into separate paired and unpaired output collections.
+  job:
+    input_collection:
+      class: Collection
+      collection_type: list:paired_or_unpaired
+      elements:
+        - identifier: el1
+          class: Collection
+          type: paired_or_unpaired
+          elements:
+            - identifier: forward
+              class: File
+              contents: "forward content"
+            - identifier: reverse
+              class: File
+              contents: "reverse content"
+        - identifier: el2
+          class: Collection
+          type: paired_or_unpaired
+          elements:
+            - identifier: unpaired
+              class: File
+              contents: "unpaired content"
+  outputs:
+    output_unpaired:
+      class: Collection
+      collection_type: list
+      elements:
+        el2:
+          asserts:
+            - that: has_text
+              text: "unpaired content"
+    output_paired:
+      class: Collection
+      collection_type: list:paired
+      elements:
+        el1:
+          elements:
+            forward:
+              asserts:
+                - that: has_text
+                  text: "forward content"
+            reverse:
+              asserts:
+                - that: has_text
+                  text: "reverse content"

lib/galaxy_test/workflow/split_paired_and_unpaired.gxwf.yml

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+class: GalaxyWorkflow
+inputs:
+  input_collection:
+    type: collection
+    collection_type: list:paired_or_unpaired
+outputs:
+  output_unpaired:
+    outputSource: split/output_unpaired
+  output_paired:
+    outputSource: split/output_paired
+steps:
+  split:
+    tool_id: '__SPLIT_PAIRED_AND_UNPAIRED__'
+    in:
+      input: input_collection