build(cmake): respect third_party_dir env variable (#3497)

* build(cmake): respect THIRD_PARTY_DIR env variable

Fixes cmake configure issue where some editor utilize CMakeLists.txt
directly

* chore(cmake): add a message

CMakeLists.txt

@@ -30,9 +30,14 @@ if (CMAKE_BUILD_TYPE STREQUAL "")
 endif ()
 
 if (NOT DEFINED CMAKE_PREFIX_PATH)
-    set(CMAKE_PREFIX_PATH "${CMAKE_SOURCE_DIR}/.deps/usr")
+    if (DEFINED ENV{THIRD_PARTY_DIR})
+        set(CMAKE_PREFIX_PATH $ENV{THIRD_PARTY_DIR})
+    else()
+        set(CMAKE_PREFIX_PATH "${CMAKE_SOURCE_DIR}/.deps/usr")
+    endif()
 endif()
 
+message (STATUS "CMAKE_PREFIX_PATH: ${CMAKE_PREFIX_PATH}")
 message (STATUS "CMAKE_BUILD_TYPE: ${CMAKE_BUILD_TYPE}")
 set(OPENMLDB_VERSION_MAJOR 0)
 set(OPENMLDB_VERSION_MINOR 8)