Integrate fmtm-splitter and remove splitting code in fmtm

[spwoodcock]

Fixes #885

Replaced split by square and split by sql query with fmtm-splitter:

• split_by_square wraps splitBySquare with params.
• split_by_sql wraps splitBySql with params.
• split_by_feature is not used, although is supported by fmtm-splitter (if we want to allow the user to provide custom task splits as a geojson).

I also moved the contributed SQL scripts from @ivangayton into the fmtm-splitter repo.

Note

Originally this included a migration to remove the tables project_aoi, ways_line, ways_poly.
I updated fmtm-splitter --> 0.2.4, which includes dropping the tables by default before creation, so the migration is no longer required (removed).