Implement Axes Symmetry functionality for Gradient Tool on Weight Paint Mode

I've originally made a Bug Report about it:

developer.blender.org/T99668

But it was Archived because it's very likely just an incomplete feature for Gradient Tool, regarding not Mirror Modifier Axes Symmetry (which works fine), but most specifically, when you've only got Axes Symmetry Options alone (and no Mirror Modifier created) from the Tool Settings Region (below Header Region) on Weight Paint Mode. It is plausible Gradient Tool would also be failing automatic 'Symmetrization' from other Painting Modes (e.g., Vertex Paint Mode).

Gradient Tool is thus incomplete on that very particular use: while every other Weight Painting Tools get their ouput Symmetrized, Gradient Tool does not. So it would be nice to have this Tool Settings Region Symmetry Options (not Mirror Modifier Symmetry Option) upgraded for Gradient Tool 'locally' (for Weight Paint Mode) or globally (in case it would be presenting this same limited behavior on other Painting Modes).

¡Thanks!