rails up to 7.0and ruby to 2.7.2

mv lib to app/lib due to upgrade

removing concerns from autoload path

resolve zeitwerk issues

make foodsoft run for dev on rails 7 and ruby 2.7

fix mail file permission bug

fix database_config

fix articles controller test ActiveModell::Error

bump Gemfile.lock

app/lib/api/errors.rb

@@ -0,0 +1,6 @@
+module Api::Errors
+  class Error < StandardError; end
+
+  # Authentication is handled by Doorkeeper, so no errors for that here
+  class PermissionRequired < Error; end
+end