SoC: stm32c0 support (#3174)

deps: Use hal_stm32 with stm32c0 USB device fixes.

Pull in ZMK fork of hal_stm32 with USB device driver fixes for stm32c0.

feat: Add nBOOT_SEL bit setup for STM32 G0/C0 targets

Newer STM32 C0 and G0 series SoCs do not by default allow use of the
BOOT0 pin/button to enter the bootloader once something has been flash
to the device, which is a change from previous series, and usually not
what's wanted for keyboards running ZMK. To address this, add some
optional, but default initialization code to check the nBOOT_SEL bit and
override it if necessary to ensure BOOT pin/button functionality.

docs: Extract bootloader config into a dedicated page.

Pull the bootloader intergration options out of the system configuration
page into their own dedicated one.

Co-authored-by: Nicolas Munnich <98408764+nmunnich@users.noreply.github.com>

---------

Co-authored-by: Nicolas Munnich <98408764+nmunnich@users.noreply.github.com>

app/west.yml

@@ -28,6 +28,12 @@ manifest:
           - openthread
           - edtt
           - trusted-firmware-m
+    - name: hal_stm32
+      revision: 4fcc3a3f32abe1c4cb76d9d1cef967728dd03908
+      path: modules/hal/stm32
+      remote: zmkfirmware
+      groups:
+        - hal
     - name: lvgl
       revision: f1db87ee98f1810328a8419572fa42a3b5f352ae
       path: modules/lib/gui/lvgl