[Android] Add android aar package (#416)

* [Android] Add Android build docs and demo (#26)

* [Backend] Add override flag to lite backend

* [Docs] Add Android C++ SDK build docs

* [Doc] fix android_build_docs typos

* Update CMakeLists.txt

* Update android.md

* [Doc] Add PicoDet Android demo docs

* [Doc] Update PicoDet Andorid demo docs

* [Doc] Update PaddleClasModel Android demo docs

* [Doc] Update fastdeploy android jni docs

* [Doc] Update fastdeploy android jni usage docs

* [Android] init fastdeploy android jar package

* [Backend] support int8 option for lite backend

* [Model] add Backend::Lite to paddle model

* [Backend] use CopyFromCpu for lite backend.

* [Android] package jni srcs and java api into aar

* Update infer.cc

* Update infer.cc

* [Android] Update package build.gradle

* [Android] Update android app examples

* [Android] update android detection app

fastdeploy/runtime.h

@@ -173,6 +173,16 @@ struct FASTDEPLOY_DECL RuntimeOption {
    */
   void DisableLiteFP16();
 
+   /**
+   * @brief enable int8 precision while use paddle lite backend
+   */
+  void EnableLiteInt8();
+
+  /**
+   * @brief disable int8 precision, change to full precision(float32)
+   */
+  void DisableLiteInt8();
+
   /**
    * @brief Set power mode while using Paddle Lite as inference backend, mode(0: LITE_POWER_HIGH; 1: LITE_POWER_LOW; 2: LITE_POWER_FULL; 3: LITE_POWER_NO_BIND, 4: LITE_POWER_RAND_HIGH; 5: LITE_POWER_RAND_LOW, refer [paddle lite](https://paddle-lite.readthedocs.io/zh/latest/api_reference/cxx_api_doc.html#set-power-mode) for more details)
    */
@@ -260,6 +270,8 @@ struct FASTDEPLOY_DECL RuntimeOption {
   // 3: LITE_POWER_NO_BIND 4: LITE_POWER_RAND_HIGH
   // 5: LITE_POWER_RAND_LOW
   LitePowerMode lite_power_mode = LitePowerMode::LITE_POWER_NO_BIND;
+  // enable int8 or not
+  bool lite_enable_int8 = false;
   // enable fp16 or not
   bool lite_enable_fp16 = false;
   // optimized model dir for CxxConfig