OpenVINS config file support (#1719)

cmake_modules/FindOpenVINS.cmake

@@ -0,0 +1,44 @@
+# Find OpenVINS
+# 
+#   We search for a vins installation in ROS/ROS2 first, then fallback on 
+#   ros-free library in common install paths
+
+FIND_PACKAGE(ov_msckf QUIET)
+IF(ov_msckf_FOUND)
+   # On ROS2, the indirect includes and libraries
+   # are not forwarded by ov_msckf target, append them manually
+   FIND_PACKAGE(ov_core)
+   FIND_PACKAGE(ov_init)
+   IF(ov_msckf_FOUND AND ov_core_FOUND AND ov_init_FOUND)
+      SET(OpenVINS_FOUND TRUE)
+      SET(OpenVINS_INCLUDE_DIRS
+         ${ov_msckf_INCLUDE_DIRS}
+         ${ov_core_INCLUDE_DIRS}
+         ${ov_init_INCLUDE_DIRS})
+      SET(OpenVINS_LIBRARIES
+         ${ov_msckf_LIBRARIES}
+         ${ov_core_LIBRARIES}
+         ${ov_init_LIBRARIES})
+   ENDIF()
+ELSE()
+   find_path(OpenVINS_INCLUDE_DIR NAMES core/VioManager.h PATH_SUFFIXES open_vins)
+   find_library(OpenVINS_LIBRARY NAMES ov_msckf_lib)
+   IF (OpenVINS_INCLUDE_DIR AND OpenVINS_LIBRARY)
+      SET(OpenVINS_FOUND TRUE)
+      SET(OpenVINS_INCLUDE_DIRS ${OpenVINS_INCLUDE_DIR})
+      SET(OpenVINS_LIBRARIES ${OpenVINS_LIBRARY})
+   ENDIF()
+ENDIF()
+
+IF (OpenVINS_FOUND)
+   # show which OpenVINS was found only if not quiet
+   IF (NOT OpenVINS_FIND_QUIETLY)
+      MESSAGE(STATUS "Found OpenVINS: ${OpenVINS_LIBRARIES} ${OpenVINS_INCLUDE_DIRS}")
+   ENDIF (NOT OpenVINS_FIND_QUIETLY)
+ELSE (OpenVINS_FOUND)
+   # fatal error if OpenVINS is required but not found
+   IF (OpenVINS_FIND_REQUIRED)
+      MESSAGE(FATAL_ERROR "Could not find OpenVINS")
+   ENDIF (OpenVINS_FIND_REQUIRED)
+ENDIF (OpenVINS_FOUND)
+