[HW] Waveshare Pico ResTouch LCD 3.5

[rexut]

Is this request related to a missing driver support for a particular hardware platform, SoC or board? Please describe.
Related to #161 I need support for the following LCD shield as part of the Raspberry Pi Pico LCD Shields collection:

• Pico ResTouch LCD 3.5

In this early first stage the Zephyr upstream samples "Shell on USB console", "Input dump", "LCD Orientation and Bit Order Test" and "LVGL Basic Sample" should be usable.

Describe why you are asking for this support?
With this support the board+shield variation for RP2040 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 shields support will coming together with RPi Pico R3 connector support as currently provided by Bridle only.