add search support for tags

[masukomi]

we should allow users to specify an array of tags in the TOML that can be used for searching.

• add new tags table (id, tag)
• add new commands_tags table (command_id, tag_id) compound key
• add handling of the tags array (if present) to Ingester
  • tags table should update before command because of triggers on command tables
• update the fts tables to have a tags column
• update the triggers to have an insert that selects from commands & joins concatenated tags

example SQL (untested of 1 of the 3 triggers)
note that SQLite uses || instead of the traditional CONCAT function and GROUP_CONCAT for concatenating rows

CREATE TRIGGER commands_fts_update AFTER UPDATE ON commands
BEGIN
    INSERT INTO commands_fts
	(commands_fts, rowid, name, description, language, tags)
	VALUES ('delete', old.rowid, old.name, old.description, old.language);

    INSERT INTO commands_fts
	(rowid, name, description, language)
	(
            SELECT GROUP_CONCAT(tag) 
                from tags where  command_id = old.id
            );
END;

[masukomi]

addressed in 1650dbf

will be released in v2