[ethernet] Add RP2040 W5500 Ethernet support

Add W5500 SPI Ethernet support for RP2040 boards using arduino-pico's
Wiznet5500lwIP class. Tested on WIZnet W5500-EVB-Pico hardware.

- Add ethernet_component_rp2040.cpp with W5500 implementation
- Add RP2040 members and setters to ethernet_component.h
- Enable RP2040 platform in SPI_SCHEMA and FILTER_SOURCE_FILES
- Add RP2040 validation, code generation, and lwIP_w5500 library
- Add W5500 RP2040 test YAML

tests/components/ethernet/common-w5500-rp2040.yaml

@@ -0,0 +1,18 @@
+ethernet:
+  type: W5500
+  clk_pin: 18
+  mosi_pin: 19
+  miso_pin: 16
+  cs_pin: 17
+  interrupt_pin: 21
+  reset_pin: 20
+  manual_ip:
+    static_ip: 192.168.178.56
+    gateway: 192.168.178.1
+    subnet: 255.255.255.0
+  domain: .local
+  mac_address: "02:AA:BB:CC:DD:01"
+  on_connect:
+    - logger.log: "Ethernet connected!"
+  on_disconnect:
+    - logger.log: "Ethernet disconnected!"

tests/components/ethernet/test-w5500.rp2040-ard.yaml

@@ -0,0 +1 @@
+<<: !include common-w5500-rp2040.yaml