New Device: Add support for ZoeRax HG0402XG V1.1

The ZoeRax HG0402XG is an unmanaged 4 2.5GBit Ethernet, 2 SFP+
device.

doc/devices/ZOERAX_HG0402XG_V1.1.md

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+### HG0402XG V1.1
+
+## Brands
+|Brand|Type|Managed|PCB|Flash|Chip RTL|
+|---|---|---|---|---|---|
+| ZoeRax | HG0402XG | No|  HG0402XG V1.1 | 1M (Winbond 25Q) | |
+
+### Label specifications
+
+- **Name**: ZOERAX 2.5G 2SFP 4-Port Gigabit Switch
+- **Model**: HG0402XG-EU
+- **Ports**:
+  - 4 × RJ45: 10/100/1000/2500 Mbps
+  - 2 × SFP+: 1000 / 2500 / 10000 Mbps
+<img src="photos/HG0402XG_V1_1/HG0402XG_V1_1_bottom.jpg" width="300" />
+
+## PCB
+
+<img src="photos/HG0402XG_V1_1/HG0402XG_V1_1_top.jpg" width="300" />
+<img src="photos/HG0402XG_V1_1/HG0402XG_V1_1_bottom.jpg" width="300" />
+
+Be aware that the UART header is metric, the pitch is 2mm. The JST PH2.0mm header shown was addeded after purchase
+
+The slider switch controls microcontroller U4 in order to configure the VLAN on/off settings. U4 can reset the SoC
+and also write into its registers to configure VLAN. With RTLPlayground the slider cannot be used for anything else
+than triggering reset. Any change in the position will trigger this reset.
+
+### Installation
+
+Using SPI clamp on-board is the only method for initial installation.
+
+### What works
+
+- All four 2.5GBASE-T RJ45 ports at 10/100/1000/2500 Mbps
+- SFP ports with various 1G/10G Fiber and Ethernet modules
+- LEDs