Update platform tests to use '.test' folder

buildroot/share/tests/start_tests

@@ -1,11 +1,17 @@
 #!/usr/bin/env bash
+#
+# start_tests
+#
+# Run one or more tests
+#
+
 export PATH="$PATH:$( cd "$(dirname "${BASH_SOURCE[0]}")" ; pwd -P )"
 export PATH="$PATH:./buildroot/bin"
 
 # exit on first failure
 set -e
 
-exec_test () {
+exec_test() {
   printf "\033[0;32m[Test $2] \033[0m$3... "
   if build_marlin_pio $1 "-e $2"; then
     printf "\033[0;32mPassed\033[0m\n"
@@ -18,9 +24,6 @@ exec_test () {
 }
 export -f exec_test
 
-env_backup
-printf "Running \033[0;32m$2\033[0m Tests\n"
-
 if [[ $3 = "--deep-clean" ]]; then
   echo "Deleting all PlatformIO caches, downloads and installed packages..."
   env_clean --deep
@@ -36,8 +39,9 @@ if [[ $2 = "ALL" ]]; then
     $f $1 $testenv
   done
 else
+  printf "Running \033[0;32m$2\033[0m Tests\n"
   exec_test $1 "$2 --target clean" "Setup Build Environment"
   $2_tests $1 $2
 fi
+
 printf "\033[0;32mAll tests completed successfully\033[0m\n"
-env_restore