Proportional Panel Sizes

[brianblakely]

Is your feature request related to a problem? Please describe.
Sometimes I need to use the Dockview APIs to build out layouts with a specific proportionality, e.g. two vertical panels occupying 30% & 70% of their container. However, Dockview's size APIs only accept a raw pixel value, which isn't very responsive to numerous window and display sizes.

Describe the solution you'd like
Perhaps for all size-related APIs, entering a number 0-1 is interpreted as a proportional input.

Describe alternatives you've considered
I have been manually reading the container's pixel dimensions and basing child panel sizes on that. However, this is not very ergonomic.