Allow users to customise the colors of FrameTimeGraph

## What problem does this solve or what need does it fill?

Some user with colour blindness (specifically red-green) may find it difficult to differentiate between the different states of the frame time graph.

## What solution would you like?

Either allow uses to specify the colours that the frame time graph uses, or add an enum with common colourblindness types and adjust colours based on variant.

If we go with the second option we should consider making it generic for all widgets and so on.

## What alternative(s) have you considered?

Not too big a deal as the height of the graph can still be used, but I still feel we should do this anyways.

Locate the FrameTimeGraph entry point and inspect how its state colors are selected and rendered. Compare the two proposed directions—user-configurable colors or color-vision variants—and define what API scope is appropriate before making a change. Done means the graph states remain distinguishable for red-green color blindness and the chosen customization behavior is covered by the relevant checks.

Written by the indexing model from the issue text.