(3/3) Add variant for pico with waveshare and GPS hat (#3412)

* (3/3) Add variant for pico with waveshare and GPS hat, utilizing slow clock.

* Not everybody has Serial2

* Trunk

* Push it real gud

* No init

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

variants/rpipico-slowclock/platformio.ini

@@ -0,0 +1,28 @@
+[env:pico_slowclock]
+extends = rp2040_base
+board = rpipico
+upload_protocol = jlink
+# debug settings for external openocd with RP2040 support (custom build)
+debug_tool = custom
+debug_init_cmds =
+  target extended-remote localhost:3333
+  $INIT_BREAK
+  monitor reset halt
+  $LOAD_CMDS
+  monitor init
+  monitor reset halt
+
+# add our variants files to the include and src paths
+build_flags = ${rp2040_base.build_flags} 
+  -DRPI_PICO
+  -Ivariants/rpipico_slowclock
+  -DDEBUG_RP2040_PORT=Serial2
+  -DHW_SPI1_DEVICE
+  -L "${platformio.libdeps_dir}/${this.__env__}/BSEC2 Software Library/src/cortex-m0plus"
+  -g
+  -DNO_USB
+lib_deps =
+  ${rp2040_base.lib_deps}
+debug_build_flags = ${rp2040_base.build_flags}
+  -g
+  -DNO_USB