Add sorting to tables

Users need to be able to sort tables by a column of their choice. These tables are;

- Gig statistics page. User should be able to sort by name, number of gigs this operating year, and total number of gigs.
- Rehearsal stats page. User should be able to sort by name and percentage/number of rehearsals attended.

Start by locating the Gig statistics and Rehearsal stats pages and their table components. Review how each table supplies its rows and displayed columns, then implement sorting for the columns listed in the issue. Done means users can choose the requested sort fields on both pages and the rows update accordingly.

Written by the indexing model from the issue text.