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/common/mapbuffer/MapBufferSoLoader.kt

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.common.mapbuffer
+
+import com.facebook.react.bridge.ReactMarker
+import com.facebook.react.bridge.ReactMarkerConstants
+import com.facebook.soloader.SoLoader
+import com.facebook.systrace.Systrace
+
+object MapBufferSoLoader {
+  @Volatile private var didInit = false
+
+  @JvmStatic
+  fun staticInit() {
+    if (didInit) {
+      return
+    }
+    didInit = true
+
+    Systrace.beginSection(
+        Systrace.TRACE_TAG_REACT_JAVA_BRIDGE,
+        "ReadableMapBufferSoLoader.staticInit::load:mapbufferjni")
+    ReactMarker.logMarker(ReactMarkerConstants.LOAD_REACT_NATIVE_MAPBUFFER_SO_FILE_START)
+    SoLoader.loadLibrary("mapbufferjni")
+    ReactMarker.logMarker(ReactMarkerConstants.LOAD_REACT_NATIVE_MAPBUFFER_SO_FILE_END)
+    Systrace.endSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE)
+  }
+}