fix bug on BSEC state storage in Flash

update BSEC configuration. Fix work_buffer size (reference example wa…

…s using wrong value_

fix long JSON strings issue: was failing since the strings were limit…

…ed to only 1 USB bulk OUT transfer (64 bytes). Detect splitted packages and increase the limit to 255 characters to accommodate more tokens

Increase heap size to avoid potential issues with the USB VCP stack