Add proxy awareness for OpenAPI spec generation

Proxy uri from command line options takes precedence over host and port

test/Feature/ProxySpec.hs

@@ -0,0 +1,13 @@
+module Feature.ProxySpec where
+
+import Test.Hspec hiding (pendingWith)
+
+import SpecHelper
+
+import Network.Wai (Application)
+
+spec :: SpecWith Application
+spec =
+  describe "GET / with proxy" $
+    it "returns a valid openapi spec with proxy" $
+      validateOpenApiResponse [("Accept", "application/openapi+json")]