devroom submissions: adding other devroom manager

[johanvdw]

When adding another devroom manger, the template will say speaker all over the place.

Ideally we can overwrite this for this specific CfP.

In any case we should make it clearer that people should add all relevant managers when they apply.

[johanvdw]

For now I've updated the code in https://github.com/johanvdw/pretalx/commits/tmp_fix_devroom_managers - which should be reverted after the devrooms CfP.

[johanvdw]

Would be nice if we can address this in pretalx for 2025:

• customize per event whether it says speaker/devroom manager/stands (stands is not using pretalx now, but should probably do so next edition).