CI: add nightly scheduled execution, perform selective test execution upon targeted platform changes

As the micro_ros_setup keeps growing and adding new features, so it does its continuous integration system.

This leds to CI executions taking too much time and often slowing the development process.
Therefore, two enhancements are proposed:

• Perform a nightly CI execution, every 24 hours, where all the tests will be run.
• Based upon the platform (host, freertos...) in which the changes are taking place, run only those tests affected by these changes. This can be easily achieved thanks to this repo's folder structure.

該 issue 提議每晚執行完整測試，並針對指定平台執行選擇性測試，但沒有指明 workflow 檔案、測試或 CI 入口點。首先定位 repository 的 CI 設定和特定平台的測試配置；完成標準是，排程的完整執行和針對變更的執行都執行預期的測試。