rhel85: add definitions of RHEL ec2 and ec2-ha images

Add new image type definitions `ec2` and `ec2-ha` representing the
official RHEL ec2 image types.

Add a `xzArchivePipeline()`, which returns a pipeline producing a XZ
archive from a file produced by a different pipeline.

Add rpmrepo snapshots for `rhui` and `ha` repositories used to generate
image test cases. `rhui` is used by the `ec2` image and it is available
on x86_64 and aarch64 architectures. `ha` is used by the `ec2-ha` image
and it is available only for x86_64.

The new image type definitions are currently not used by any
API test case.

Signed-off-by: Tomas Hozza <thozza@redhat.com>

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

@@ -10,6 +10,28 @@
     },
     "overrides": {}
   },
+  "ec2": {
+    "compose-request": {
+      "distro": "",
+      "arch": "",
+      "image-type": "ec2",
+      "repositories": [],
+      "filename": "image.raw.xz",
+      "blueprint": {}
+    },
+    "overrides": {}
+  },
+  "ec2-ha": {
+    "compose-request": {
+      "distro": "",
+      "arch": "",
+      "image-type": "ec2-ha",
+      "repositories": [],
+      "filename": "image.raw.xz",
+      "blueprint": {}
+    },
+    "overrides": {}
+  },
   "edge-commit": {
     "compose-request": {
       "distro": "",