Restore WiFi flags dropped from ThinkNode M7 companion wifi env in upstream merge

The upstream/dev merge kept our side of variants/thinknode_m7/platformio.ini,
losing -D ENABLE_WIFI_INTERFACE and +<helpers/wifi/*.cpp>. Companion WiFi is
now gated on that flag, so the env built silently without WiFi.

variants/thinknode_m7/platformio.ini

@@ -136,6 +136,7 @@ extends = ThinkNode_M7
 build_flags =
   ${ThinkNode_M7.build_flags}
   -I examples/companion_radio/ui-orig
+  -D ENABLE_WIFI_INTERFACE
   -D MAX_CONTACTS=350
   -D MAX_GROUP_CHANNELS=40
   -D DISPLAY_CLASS=NullDisplayDriver
@@ -146,6 +147,7 @@ build_flags =
 ;  -D MESH_PACKET_LOGGING=1
 build_src_filter = ${ThinkNode_M7.build_src_filter}
   +<helpers/esp32/*.cpp>
+  +<helpers/wifi/*.cpp>
   +<helpers/ui/MomentaryButton.cpp>
   +<helpers/ui/NullDisplayDriver.cpp>
   +<../examples/companion_radio/*.cpp>