`map_exists=False` scenarios should be included in main database

[ar-siddiqui]

Ignoring them cause erroneous increase in WSEL.

Implementation plan is:

• Add a column to scenarios (previously rating_curves) table map_exists
• Default it to True
• Move rows from scnearios_no_map to scenarios table with map_exists false
• Update flows2fim to ignore these files in fim command