[MLU] add some basic support for MLU, including related passes, kernels, gtests and some api in padddle_api.h
Passes：mlu_subgraph_pass ,mlu_postprocess_pass
Kernels:  act，batch_norm, concat, conv, elementwise, fc, interpolate, pool, scale, softmax

* Support bitman backend

X86 and cuda compile simutaneously cmake ..  -DCMAKE_BUILD_TYPE=RelWithDebInfo  -DWITH_MKL=ON           -DLITE_WITH_CUDA=ON           -DWITH_MKLDNN=OFF           -DLITE_WITH_X86=ON           -DLITE_WITH_PROFILE=OFF          -DWITH_LITE=OFF           -DLITE_WITH_LIGHT_WEIGHT_FRAMEWORK=OFF           -DWITH_PYTHON=OFF           -DWITH_TESTING=ON           -DLITE_WITH_ARM=OFF           -DLITE_ON_TINY_PUBLISH=OFF           -DCUDNN_ROOT=/usr/local/cudnn/           -DLITE_BUILD_EXTRA=ON (#2708)

x86 and cuda compile simutaneously

[LITE][NPU][XPU] Refine subgraph pass, and support NPU/XPU model generation at execution time (#2576)

* Initial support for XPU
* Fix compiling errors of XPU
* Move XPU op kernel bridges from backends to kernels to fix deps order
* Change the namespace and directory of XPU bridges
* Add XPU SDK
* Fix header files and namespace of XPU SDK
* Add unit tests for relu and conv2d ops
* Restore the modification of paddle_api_test
* Supports simple model which contains only a relu layer
* Add compiling scripts for XPU
* Fix compiling errors of XPU
* Add comments for XPU LoadModel and BuildModel