[build][cmake] Improve cmake config file generation (#4541)

* Improve cmake config file generation

This allows for finding raylib on a non-standard location (eg, not in /usr/lib{,64})

* Only have glfw as private if using internal glfw and not static

cmake/SetupCmakeConfig.cmake

@@ -0,0 +1,23 @@
+include(CMakePackageConfigHelpers)
+include(GNUInstallDirs)
+
+# Setup install of exported targets
+install(EXPORT raylib-targets
+  DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/raylib
+)
+
+# Macro to write config
+write_basic_package_version_file(
+  "${CMAKE_CURRENT_BINARY_DIR}/raylib-config-version.cmake"
+  VERSION ${raylib_VERSION}
+  COMPATIBILITY SameMajorVersion
+)
+
+# Setup install of version config
+install(
+  FILES
+    "../cmake/raylib-config.cmake"
+    "${CMAKE_CURRENT_BINARY_DIR}/raylib-config-version.cmake"
+  DESTINATION
+   ${CMAKE_INSTALL_LIBDIR}/cmake/raylib
+)