Allow users to enter an existing key when adding a channel

Allow the key field to be edited by a user and validate that the user supplied key is valid base64 encoded and the correct key length.

Meshtastic/Views/Settings/Channels.swift

@@ -25,6 +25,7 @@ struct Channels: View {
 	var node: NodeInfoEntity?
 
 	@State var hasChanges = false
+	@State var hasValidKey = false
 	@State private var isPresentingEditView = false
 	@State private var isPresentingSaveConfirm: Bool = false
 	@State private var channelIndex: Int32 = 0
@@ -167,9 +168,33 @@ struct Channels: View {
 						HStack(alignment: .top) {
 							Text("Key")
 							Spacer()
-							Text(channelKey)
-								.foregroundColor(Color.gray)
-								.textSelection(.enabled)
+							TextField(
+								"Key",
+								text: $channelKey
+							)
+							.disableAutocorrection(true)
+							.keyboardType(.alphabet)
+							.foregroundColor(Color.gray)
+							.textSelection(.enabled)
+							.background(
+								RoundedRectangle(cornerRadius: 25.0)
+									.stroke(
+										hasValidKey ?
+										Color.green :
+										Color.red
+										, lineWidth: 2.0)
+							)
+							.onChange(of: channelKey, perform: { _ in
+								let tempKey = Data(base64Encoded: channelKey) ?? Data()
+								if tempKey.count == channelKeySize || channelKeySize == -1{
+									hasValidKey = true
+								}
+								else {
+									hasValidKey = false
+								}
+								hasChanges = true
+							})
+							.disabled(channelKeySize <= 0)
 //							TextField(
 //								"",
 //								text: $channelKey,
@@ -256,7 +281,7 @@ struct Channels: View {
 						} label: {
 							Label("save", systemImage: "square.and.arrow.down")
 						}
-						.disabled(bleManager.connectedPeripheral == nil || !hasChanges)
+						.disabled(bleManager.connectedPeripheral == nil || !hasChanges || !hasValidKey)
 						.buttonStyle(.bordered)
 						.buttonBorderShape(.capsule)
 						.controlSize(.large)