Add encoder for aptX and encoder for aptX HD source code.

system/embdrv/encoder_for_aptx/include/aptXbtenc.h

system/embdrv/encoder_for_aptx/src/AptxEncoder.h

system/embdrv/encoder_for_aptx/src/AptxParameters.h

system/embdrv/encoder_for_aptx/src/AptxTables.h

system/embdrv/encoder_for_aptx/src/CBStruct.h

system/embdrv/encoder_for_aptx/src/CodewordPacker.h

system/embdrv/encoder_for_aptx/src/DitherGenerator.h

system/embdrv/encoder_for_aptx/src/ProcessSubband.c

system/embdrv/encoder_for_aptx/src/Qmf.h

system/embdrv/encoder_for_aptx/src/QmfConv.c

system/embdrv/encoder_for_aptx/src/QuantiseDifference.c

system/embdrv/encoder_for_aptx/src/Quantiser.h

system/embdrv/encoder_for_aptx/src/SubbandFunctions.h

system/embdrv/encoder_for_aptx/src/SubbandFunctionsCommon.h

system/embdrv/encoder_for_aptx/src/SyncInserter.h

system/embdrv/encoder_for_aptx/src/aptXbtenc.c

system/embdrv/encoder_for_aptx/src/swversion.h

system/embdrv/encoder_for_aptxhd/include/aptXHDbtenc.h

system/embdrv/encoder_for_aptxhd/src/AptxEncoder.h

system/embdrv/encoder_for_aptxhd/src/AptxParameters.h