[HW] Waveshare Pico Clock Green

[rexut]

Is this request related to a missing driver support for a particular hardware platform, SoC or board? Please describe.
I need support for Waveshare Pico Clock Green as shield. The following shield should be supported:

• Waveshare Pico Clock Green

In this early first stage the Zephyr upstream samples "Shell on USB console", "LCD Orientation and Bit Order Test" should be usable. Access to the RTC and temperature sensor is optional.

Describe why you are asking for this support?
With this support the board+shield variation for display based systems will scaling up.

I'm preparing a changeset for PR. I'll maintain the new board for Bridle and later contribute and maintain to/in Zephyr upstream.

Additional context
The new shield support will coming together with Raspberry Pi Pico (W) and Waveshare RP2040-Plus board support as currently provided by Bridle only.