Improve BPE flow diagram and gf Python code

[ThomasPO]

BPE flow diagram

• add code lists generation to bpe flow diagram
• redesign of the BPE workflow diagram

Python code

• fix: CSVW generation and code list generation
• add write code list files on ftp
• add csv files describing variables for french facilities
• apply filtering of facilities to metadata extracted
• add json serialization for csvw python dictionary and load to ftp
• add metadata transformation to csvw python dictionary
• add second metadata file extracted
• recode variable QUALITE_XY
• add second data file extracted and add a concatenate task
• switch int type to Int64 and use of dtype for extracting data + add filter for selecting Exhibition places and heritage CSVW

population-sample.csv-metadata.json

• add title, description and creator to the root and change name for nuts3 references