tools: test cases for alt kernel selection

Two new test cases added to format-request-map and test cases are
generated.

1. kernel-rt for RHEL images:
Requires new package repositories for RHEL 8.3 and 8.4.
Creates an OSTree commit with the `kernel-rt` as a customization.

2. kernel-debug for Fedora images:
kernel-rt isn't included in the official fedora repositories.  Using
kernel-debug at least tests the feature with the fedora-iot-commit type.

tools/test-case-generators/format-request-map.json

@@ -24,6 +24,23 @@
     },
     "overrides": {}
   },
+  "rhel-edge-commit-rt": {
+    "compose-request": {
+      "distro": "",
+      "arch": "",
+      "image-type": "rhel-edge-commit",
+      "repositories": [],
+      "filename": "commit.tar",
+      "blueprint": {
+        "customizations": {
+          "kernel": {
+            "name": "kernel-rt"
+          }
+        }
+      }
+    },
+    "overrides": {}
+  },
   "fedora-iot-commit": {
     "compose-request": {
       "distro": "",
@@ -35,6 +52,23 @@
     },
     "overrides": {}
   },
+  "fedora-iot-commit-debug": {
+    "compose-request": {
+      "distro": "",
+      "arch": "",
+      "image-type": "fedora-iot-commit",
+      "repositories": [],
+      "filename": "commit.tar",
+      "blueprint": {
+        "customizations": {
+          "kernel": {
+            "name": "kernel-debug"
+          }
+        }
+      }
+    },
+    "overrides": {}
+  },
   "openstack": {
     "boot": {
       "type": "openstack"