restructure agora-scripts modules

In order to allow reusing this code in the future, I've made it so that
Agora-specific code all lives in `Main`, and everything else lives in
`ScriptExport` or other non-Agora modules.

agora-scripts/ScriptExport/Options.hs

@@ -0,0 +1,39 @@
+{- |
+Module     : ScriptExport.Options
+Maintainer : emi@haskell.fyi
+Description: Command line options for 'agora-scripts'.
+
+Command line options for 'agora-scripts'.
+-}
+module ScriptExport.Options (Options (..), parseOptions) where
+
+import Network.Wai.Handler.Warp qualified as Warp
+import Options.Applicative ((<**>))
+import Options.Applicative qualified as Opt
+
+newtype Options = Options
+  { port :: Warp.Port
+  }
+  deriving stock (Show, Eq)
+
+opt :: Opt.Parser Options
+opt =
+  Options
+    <$> Opt.option
+      Opt.auto
+      ( Opt.long "port"
+          <> Opt.short 'p'
+          <> Opt.metavar "PORT"
+          <> Opt.value 3939
+          <> Opt.help "The path where the script configuration is."
+      )
+
+parseOptions :: IO Options
+parseOptions = Opt.execParser p
+  where
+    p =
+      Opt.info
+        (opt <**> Opt.helper)
+        ( Opt.fullDesc
+            <> Opt.progDesc "Generate Agora scripts for off-chain use."
+        )