Add support for Adafruit Feather RP2040 with RFM95. (#4451)

* Add support for Adafruit Feather RP2040 with RFM95.

* Update mesh.pb.h

dropping this change from the file generated by the protobuf

* Update mesh.pb.h

remove these reverting changes

* Update mesh.pb.h

oops, missed a comma

variants/feather_rp2040_rfm95/platformio.ini

@@ -0,0 +1,16 @@
+[env:feather_rp2040_rfm95]
+extends = rp2040_base
+board = adafruit_feather
+upload_protocol = picotool
+
+# add our variants files to the include and src paths
+build_flags = ${rp2040_base.build_flags} 
+  -DRP2040_FEATHER_RFM95
+  -Ivariants/feather_rp2040_rfm95
+  -DDEBUG_RP2040_PORT=Serial
+  -DHW_SPI1_DEVICE
+  -L "${platformio.libdeps_dir}/${this.__env__}/bsec2/src/cortex-m0plus"
+lib_deps =
+  ${rp2040_base.lib_deps}
+debug_build_flags = ${rp2040_base.build_flags}
+debug_tool = cmsis-dap ; for e.g. Picotool