fixed time.h import, added Arduino UNO R4 minima (USB), Arduino UNO R4 WiFi (USB and WiFi), Arduino Giga R1 (USB and WiFi) (backport #1712)

[mergify]

By importing time.h instead of sys/time.h you can build micro-ros for Arduino UNO R4.

It addresses issue: #1461

This PR was tested on following targets:

• mbed (Arduino GIGA R1)
• m4 (Arduino UNO R4 Minima)
• stm32 (STMicroelectronics Nucleo F401RE)

---

This is an automatic backport of pull request #1712 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of e347a4a has failed:

On branch mergify/bp/rolling/pr-1712
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Changes to be committed:
	modified:   library.properties
	modified:   src/default_transport.cpp

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	both modified:   .github/workflows/ci.yml
	both modified:   README.md
	both modified:   examples/micro-ros_publisher_wifi/micro-ros_publisher_wifi.ino
	deleted by us:   examples/micro-ros_publisher_wifi_at/micro-ros_publisher_wifi_at.ino
	both modified:   src/micro_ros_arduino.h
	both modified:   src/wifi_transport.cpp

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally