ENHANCE: allow to use local install of Catch2 library or download latest available

unit_tests/CMakeLists.txt

-Include(FetchContent)
+find_package(Catch2 REQUIRED)
 
-FetchContent_Declare(
-  Catch2
-  GIT_REPOSITORY https://github.com/catchorg/Catch2.git
-  GIT_TAG        v3.7.1 # or a later release
-)
+if(NOT Catch2_FOUND)
+    message(STATUS "Catch2 not found in system, retrieving from git")
+    Include(FetchContent)
 
-FetchContent_MakeAvailable(Catch2)
+    FetchContent_Declare(
+      Catch2
+      GIT_REPOSITORY https://github.com/catchorg/Catch2.git
+      GIT_TAG        devel # or a later release
+    )
+
+    FetchContent_MakeAvailable(Catch2)
+else()
+    message(STATUS "Found system Catch2 version ${Catch2_VERSION}")
+endif()
 
 file(GLOB_RECURSE src_files "*.cpp")