DragonX SDK: increase batch size and update server endpoints

- Increase DOWNLOAD_BATCH_SIZE from 50 to 500 for faster sync
- Update default server endpoints to dragonx.is (mainnet and testnet)
- Add jniLibs source dir for Rust native libraries in build config

sdk-lib/src/main/java/cash/z/ecc/android/sdk/ext/ZcashSdk.kt

@@ -35,9 +35,9 @@ object ZcashSdk {
      * Default size of batches of blocks to request from the compact block service.
      */
     // Because blocks are buffered in memory upon download and storage into SQLite, there is an upper bound
-    // above which OutOfMemoryError is thrown. Experimentally, this value is below 50 blocks.
-    // Back of the envelope calculation says the maximum block size is ~100kb.
-    const val DOWNLOAD_BATCH_SIZE = 50
+    // above which OutOfMemoryError is thrown. DragonX compact blocks are small (~1-2kb each),
+    // so a larger batch size significantly reduces gRPC call overhead during initial sync.
+    const val DOWNLOAD_BATCH_SIZE = 500
 
     /**
      * Default size of batches of blocks to scan via librustzcash. The smaller this number the more granular information

sdk-lib/src/main/java/cash/z/ecc/android/sdk/internal/service/LightWalletGrpcService.kt

@@ -164,14 +164,6 @@ class LightWalletGrpcService private constructor(
                 .enableFullStreamDecompression()
                 .apply {
                     useTransportSecurity()
-                   /*
-                    if (lightWalletEndpoint.isSecure) {
-                        useTransportSecurity()
-                    } else {
-                        twig("WARNING: Using insecure channel")
-                        usePlaintext()
-                    }
-                    */
                 }
                 .build()
         }

sdk-lib/src/main/java/cash/z/ecc/android/sdk/model/LightWalletEndpointExt.kt

@@ -24,14 +24,14 @@ private const val DEFAULT_PORT = 443
 
 val LightWalletEndpoint.Companion.Mainnet
     get() = LightWalletEndpoint(
-        "dragonlite.printogre.com",
+        "lite.dragonx.is",
         DEFAULT_PORT,
         isSecure = true
     )
 
 val LightWalletEndpoint.Companion.Testnet
     get() = LightWalletEndpoint(
-        "dragonlite.printogre.com",
+        "lite.dragonx.is",
         DEFAULT_PORT,
         isSecure = true
     )