1. modify the limit of frames to send to avoid dropping packet on A2DP source due to TX data queue overflow
2. reduce the A2DP source data queue size in order to achieve faster control respnonse
1. Change all the hash used from the coap module to generated by the bluedroid module directly.
component/bt: Added the <string.h> include file to the gattc_co module to avoid compile error.
1. add the L1 include path with a prefix, such like osi/list.h, stack/a2d_api.h and etc.
2. modify component, only bluedroid/api/include/api is export to another component and application,
other include path just for bluedroid used
3. put bluedroid/include into common/include/common, so the root directory of bluedroid have no include path.
4. modify doxygen to use esp_bt.h and redirect to
component/bt/bluedroid/api/include/api/
fix compile
