chore: update ImGui configuration and remove legacy CMake file

- Incremented cache revision in dependencies.lock to trigger rebuild.
- Deleted obsolete imgui.cmake file to streamline project structure.
- Updated imgui.cmake to set C++ standard requirement for ImGui and its test engine.

Benefits:
- Simplifies dependency management and ensures compatibility with C++17.
- Cleans up unused files, improving project maintainability.

cmake/dependencies/imgui.cmake

@@ -25,6 +25,9 @@ target_include_directories(ImGui PUBLIC
   ${IMGUI_DIR}/backends
 )
 
+# Set C++ standard requirement (ImGui 1.90+ requires C++11, we use C++17 for consistency)
+target_compile_features(ImGui PUBLIC cxx_std_17)
+
 # Link to SDL2
 target_link_libraries(ImGui PUBLIC ${YAZE_SDL2_TARGETS})
 
@@ -52,6 +55,7 @@ if(YAZE_BUILD_TESTS)
       ${IMGUI_TEST_ENGINE_DIR}
       ${CMAKE_SOURCE_DIR}/src/lib
     )
+    target_compile_features(ImGuiTestEngine PUBLIC cxx_std_17)
     target_link_libraries(ImGuiTestEngine PUBLIC ImGui ${YAZE_SDL2_TARGETS})
     target_compile_definitions(ImGuiTestEngine PUBLIC
       IMGUI_ENABLE_TEST_ENGINE=1