feat: allow users to enable herokuish usage on arm/arm64 platforms

While the majority of buildpacks do not work on non-amd64 platforms, this will at least allow developers the option to choose when to override this setting.

tests/unit/builder-herokuish.bats

@@ -17,3 +17,74 @@ teardown() {
   assert_success
   assert_output_contains 'DOTENV_KEY=some_value'
 }
+
+@test "(builder-herokuish) builder-herokuish:set allowed" {
+  if [[ "$(dpkg --print-architecture 2>/dev/null || true)" == "amd64" ]]; then
+    skip "this test cannot be performed accurately on amd64 as it tests whether we can enable the plugin on armhf/arm64"
+  fi
+
+  run /bin/bash -c "dokku builder-herokuish:set --global allowed"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku builder-herokuish:report $TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run deploy_app
+  echo "output: $output"
+  echo "status: $status"
+  assert_failure
+
+  run create_app
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku builder-herokuish:set --global allowed true"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku builder-herokuish:report $TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run deploy_app
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku builder-herokuish:set --global allowed"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku builder-herokuish:set $TEST_APP allowed true"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku builder-herokuish:report $TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku ps:rebuild $TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku builder-herokuish:set $TEST_APP allowed"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku ps:rebuild $TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_failure
+}