refactor: maps (#2097)

Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>

app/src/main/java/com/geeksville/mesh/util/SharedPreferenceExtensions.kt

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2025 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.geeksville.mesh.util
+
+import android.content.SharedPreferences
+import androidx.core.content.edit
+import kotlinx.coroutines.flow.MutableStateFlow
+
+fun SharedPreferences.toggleBooleanPreference(
+    state: MutableStateFlow<Boolean>,
+    key: String,
+    onChanged: (Boolean) -> Unit = {},
+) {
+    val newValue = !state.value
+    state.value = newValue
+    this.edit { putBoolean(key, newValue) }
+    onChanged(newValue)
+}