* add MILVUS_SUPPORT_SPTAG for some code
Signed-off-by: Nyudong.cai <yudong.cai@zilliz.com>

* use knowhere::IndexEnum in db
Signed-off-by: Nyudong.cai <yudong.cai@zilliz.com>

* keep EngineType order
Signed-off-by: Nyudong.cai <yudong.cai@zilliz.com>