Adapt ReadableMapBuffer to MapBuffer interface

Summary:
Updates `ReadableMapBuffer` to conform to `MapBuffer` interface, to allow interchangeable use of `Readable/WritableMapBuffer` in the code.

Notable changes:
- MapBuffer.Entry getters are now represented as Kotlin properties and appended `Value` suffix (e.g. `entry.getInt()` becomes `entry.getIntValue()` in Java, or `entry.intValue` in Kotlin)
- `ByteBuffer` is imported in constructor instead of on demand. This method doesn't copy the data as the bytes are read directly from native heap, and benchmarking a 500-byte `MapBuffer` shows no difference in import speed.
- Internal logic of `ReadableMapBuffer` uses `UShort` kotlin type for key retrieval, for more correct representation of values.
- Explicit exception throws are replaced with `require` and `check` methods for `IllegalArgumentException` and `IllegalStateException` (default FB conversion).

The change also updates `ReadableMapBuffer` usages to `MapBuffer` interface where possible (virtually everywhere except JNI methods).

Changelog: [Android][Changed] - Adopt `MapBuffer` interface for `ReadableMapBuffer`

Reviewed By: mdvacca

Differential Revision: D35218633

fbshipit-source-id: 515dd974c27b2978ade325b2e1750ab8f068a20a

ReactAndroid/src/main/java/com/facebook/react/fabric/FabricJSIModuleProvider.java

@@ -11,7 +11,7 @@ import androidx.annotation.NonNull;
 import com.facebook.react.bridge.JSIModuleProvider;
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.bridge.UIManager;
-import com.facebook.react.common.mapbuffer.ReadableMapBufferSoLoader;
+import com.facebook.react.common.mapbuffer.MapBufferSoLoader;
 import com.facebook.react.config.ReactFeatureFlags;
 import com.facebook.react.fabric.events.EventBeatManager;
 import com.facebook.react.uimanager.ViewManagerRegistry;
@@ -46,7 +46,7 @@ public class FabricJSIModuleProvider implements JSIModuleProvider<UIManager> {
     final Binding binding = new Binding();
 
     if (ReactFeatureFlags.isMapBufferSerializationEnabled()) {
-      ReadableMapBufferSoLoader.staticInit();
+      MapBufferSoLoader.staticInit();
     }
 
     binding.register(