webapi: remove attribute point gain after level cutoff

[Muparadzi]

Reworked attribute point gain to reduce the significant advantage provided by high levels.

• 1 extra starting attribute point
• 1 extra starting skill points

Levels achieved after level 30 will no longer award an attribute point.

Added respec all characters API endpoint which will be required to scale all characters to new model.

Updated skill builder to reflect changes

[or2e]

I'll take a look, I still need to update the frontend doc and ui spec (I will)

[Meowkov]

Looking good