add kiss radio env to most of the variants

variants/heltec_mesh_solar/platformio.ini

@@ -92,4 +92,9 @@ build_src_filter = ${Heltec_mesh_solar.build_src_filter}
   +<../examples/companion_radio/*.cpp>
 lib_deps =
   ${Heltec_mesh_solar.lib_deps}
-  densaugeo/base64 @ ~1.4.0
+  densaugeo/base64 @ ~1.4.0
+
+[env:Heltec_mesh_solar_kiss_modem]
+extends = Heltec_mesh_solar
+build_src_filter = ${Heltec_mesh_solar.build_src_filter}
+  +<../examples/kiss_modem/>