✨ Implement port connection dialog

Implements:
- Viewing connections (routes)
- Creating and deleting connections
- Changing volume of connectons
- Muting / unmuting connections

lib/port_connection_dialog.dart

@@ -0,0 +1,132 @@
+import 'dart:math';
+import 'package:flutter/material.dart';
+import 'package:gomix_flutter/mixer_state.dart' as mixer;
+import 'package:gomix_flutter/mixing_card.dart';
+import 'package:gomix_flutter/port_connection_card.dart';
+import 'package:gomix_flutter/ports_tab.dart';
+
+class PortConnectionDialog extends StatefulWidget {
+  final Function(Map<String, Object> data) sendAction;
+  final mixer.Port port;
+  final bool isOutput;
+  final DialogDataModel dataModel;
+  final mixer.MixerState mixerState;
+
+  const PortConnectionDialog(
+      {super.key,
+      required this.sendAction,
+      required this.port,
+      required this.dataModel,
+      this.isOutput = false,
+      required this.mixerState});
+
+  void show(BuildContext context) {
+    showDialog<String>(
+      context: context,
+      builder: (BuildContext context) => AlertDialog(
+        title: isOutput
+            ? Text("Inputs > ${port.name}")
+            : Text("${port.name} > Outputs"),
+        content: this,
+      ),
+    );
+  }
+
+  void showNewConnectionDialog(BuildContext context) {
+    showDialog<String>(
+      context: context,
+      builder: (BuildContext context) => AlertDialog(
+        title: const Text("New connection"),
+        content: PortsTab(
+          mixerState: mixerState,
+          sendAction: sendAction,
+          // Can only select outputs if source port is an input and nice versa
+          filter: (_, isOutput) => this.isOutput != isOutput,
+          selectionCallback: (destination) {
+            Navigator.pop(context);
+            sendAction({
+              "method": "createRoute",
+              "UUID": isOutput ? destination.uuid : port.uuid,
+              "routeData": {"to": isOutput ? port.uuid : destination.uuid}
+            });
+          },
+        ),
+      ),
+    );
+  }
+
+  @override
+  State<PortConnectionDialog> createState() => _PortConnectionState();
+}
+
+class _PortConnectionState extends State<PortConnectionDialog> {
+  List<(mixer.Port, mixer.State)> connections = [];
+
+  List<(mixer.Port, mixer.State)> getConnections() {
+    List<(mixer.Port, mixer.State)> connections = [];
+    if (widget.isOutput) {
+      for (mixer.Port input in widget.dataModel.mixerState.inputs) {
+        for (mixer.State connection in input.route) {
+          String toUUID = connection.toUuid ?? "";
+          if (toUUID == widget.port.uuid) connections.add((input, connection));
+        }
+      }
+    } else {
+      connections = widget.dataModel.port.route
+          .map((route) => (widget.port, route))
+          .toList();
+    }
+    return connections;
+  }
+
+  var dataModelListener = () {};
+
+  @override
+  void initState() {
+    super.initState();
+    connections = getConnections();
+
+    dataModelListener = () {
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        setState(() {
+          connections = getConnections();
+        });
+      });
+    };
+    widget.dataModel.addListener(dataModelListener);
+  }
+
+  @override
+  void dispose() {
+    widget.dataModel.removeListener(dataModelListener);
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return SizedBox(
+      width: min(MediaQuery.of(context).size.width, 400),
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        crossAxisAlignment: CrossAxisAlignment.stretch,
+        children: (connections
+                .map((elem) => PortConnectionCard(
+                    sourcePort: elem.$1,
+                    connection: elem.$2,
+                    isOutput: widget.isOutput,
+                    mixerState: widget.mixerState,
+                    sendAction: widget.sendAction) as Widget)
+                .toList()) +
+            <Widget>[
+              const SizedBox(height: 10),
+              TextButton.icon(
+                  onPressed: () {
+                    widget.showNewConnectionDialog(context);
+                  },
+                  icon: const Icon(Icons.add),
+                  label: const Text("New connection"))
+            ],
+      ),
+    );
+  }
+}