Introduce Hilt dependency injection

Uses Hilt to get the database initialization off of the
main thread.

The initial introduction always has a disproportionate
fan-out of boilerplate. In this case, all entry points which
were using UIViewModel needed to be annotated in order to let
the code gen know that they needed to support it.

The PacketRepository is injected into things via the main
thread (e.g., the MeshService) but due to the lazy declaration,
the database isn't hydrated until the DAO is access while on an
IO thread.

app/src/main/java/com/geeksville/mesh/database/DatabaseModule.kt

@@ -0,0 +1,29 @@
+package com.geeksville.mesh.database
+
+import android.app.Application
+import androidx.room.Room
+import com.geeksville.mesh.database.dao.PacketDao
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+
+@InstallIn(SingletonComponent::class)
+@Module
+class DatabaseModule {
+    @Provides
+    fun provideDatabase(application: Application): MeshtasticDatabase {
+        return Room.databaseBuilder(
+            application.applicationContext,
+            MeshtasticDatabase::class.java,
+            "meshtastic_database"
+        )
+            .fallbackToDestructiveMigration()
+            .build()
+    }
+
+    @Provides
+    fun providePacketDao(database: MeshtasticDatabase): PacketDao {
+        return database.packetDao()
+    }
+}