appid: Exclude Devel suffixes from domain check

when an extra devel suffix gets added to the original appid, the
rDNS check will take in all components of the appid but their might not
be a webpage available there. So standardise on the `Devel` suffix
and skip on that.

Devel is not to be allowed on Flathub submission, submission reviews
need to take note of that

flatpak_builder_lint/checks/appid.py

@@ -56,6 +56,8 @@ def _validate(self, appid: Optional[str], is_extension: bool) -> None:
         if appid:
             if is_extension or is_baseapp:
                 return
+            if split[-1] == "Devel":
+                return
             if domainutils.is_app_on_flathub(appid):
                 return
             if appid.startswith(domainutils.code_hosts):

tests/manifests/domain_checks/ch.wwwwww.bar.Devel.json

@@ -0,0 +1,13 @@
+{
+    "app-id": "ch.wwwwww.bar.Devel",
+    "runtime": "foo",
+    "sdk": "bar",
+    "command": "foo",
+    "finish-args": ["--foo=bar"],
+    "modules": [
+        {
+            "name": "module2",
+            "buildsystem": "autotools"
+        }
+    ]
+}

tests/test_manifest.py

@@ -27,6 +27,11 @@ def test_appid_too_many_cpts() -> None:
     assert {"appid-too-many-components-for-app"} == errors
 
 
+def test_appid_devel_skip() -> None:
+    ret = run_checks("tests/manifests/domain_checks/ch.wwwwww.bar.Devel.json")
+    assert "errors" not in ret
+
+
 def test_appid_url_not_reachable() -> None:
     for i in (
         "tests/manifests/domain_checks/io.github.wwwwwwwwwwwww.bar.json",