A flutter sample app that connects to local canister

1. dfx installed to your local machine, making sure you can deploy canister to your local machine.
2. flutter installed, and use flutter doctor -v make sure everything works
3. flutter pub get before running this example.
4. If you want to use MacOS to debug, make sure macos/Runner/DebugProfile.entitlements and macos/Runner/Release.entitlements have content below

   <dict>
       ...
       <key>com.apple.security.network.client</key>
       <true/>
   </dict>

5. Deploy canister use dfx deploy, the counter canister will be running on your local replica. Make sure you put the counter canister id inside .dfx/local/canister_ids.json to your main.dart, the json like this:

   {
       "__Candid_UI": {
           "local": "x2dwq-7aaaa-aaaaa-aaaxq-cai"
       },
       "counter": {
           "local": "x5cqe-syaaa-aaaaa-aaaxa-cai"
       }
   }

6. inside main.dart, you should change settings with canisterId to your actual id.

    Future<void> initCounter({Identity? identity}) async {
        
        // initialize counter, change canister id here
        counter = Counter(canisterId: 'x5cqe-syaaa-aaaaa-aaaxa-cai', url: 'http://localhost:8000');
        // set agent when other paramater comes in like new Identity
        await counter?.setAgent(newIdentity: identity);
        
    }

7. start

   flutter run