Add gender support to the GrimoireLab toolchain

This task aims at building a proper gender support across the several tools available in GrimoireLab.

The following pieces are required from the best of my understanding:
* SortingHat: Add gender support, being this a new entry in the profile of the community member
* https://github.com/chaoss/grimoirelab-sortinghat/issues/128
* Gelk: Add gender support when returning info about a specific community member
* https://github.com/chaoss/grimoirelab-elk/issues/218
* Sigils: Specific and anonymous panels to display gender information
* https://github.com/chaoss/grimoirelab-sigils/issues/160
* Others: tools not covered in this ticket

This ticket will likely have an iterative process and other tools or requirements could be later added.

Start by reading the linked SortingHat issue #128, Gelk issue #218, and Sigils issue #160 to understand each tool's required scope and interfaces. Map how gender data would move across these components and identify any additional tools affected. Done means the agreed support is implemented consistently across the listed pieces, with the remaining requirements clarified.

Written by the indexing model from the issue text.