delete _fts tables with --replace-tables

[JBPressac]

Hello,
I suggest the deletion of the _fts tables in case of use of the -f and --replace-tables options. Otherwise, an error occurs warning that the _fts tables already exist when csvs-to-sqlite is run on existing tables with FTS support.
Thank you,

[simonw]

Good idea!

[simonw]

sqlite-utils has a disable_fts() method I could use here: https://sqlite-utils.readthedocs.io/en/stable/python-api.html#enabling-full-text-search