* add gpu cache config handler
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* remove cpu/gpu cache mgr from Config class by using cache config handler (fix #1572)
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* remove 0.8.0 from config version map
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* clean config header reference
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* fix bug in web readme
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* reduce gpu config handler to gpu resources handler
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* add engine config
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* modify handler hook(fix #1572)
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* update changlog
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* initalize value in handler by config default
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* code style format
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* fix compile error in release mode
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* resolve faiss blas threshold init in DBWrapper
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* modify cache header
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* remove comments
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* order headers
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* convert gpu res config to lower case
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* CI retry
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* adjust header order in cpu cache mar file
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* improve config test case
Signed-off-by: NYhz <yinghao.zou@zilliz.com>

* code format
Signed-off-by: NYhz <yinghao.zou@zilliz.com>