Added flag to disable check for sketch foldername matching sketch name

[cmaglie]

This is required to ensure backward compatibility for arduino-builder that doesn't enforce this check.

In particular, since arduino-builder is used in the Arduino IDE, if the user tries to compile an unsaved sketch, the Arduino IDE will create a temporary copy of the sketch in a temp dir with a random name: in this case if the folder name check is enabled the compile will fail.

This flag is for internal use only (basically only on arduino-builder) it will be removed once arduino-builder will be completely replaced by arduino-cli in the Arduino IDE.