Add options to high level generators for excluding areas from the navmesh

[isaac-mason]

Supporting all custom area functionality in the high level generators is probably going to be complex, but we could add options for marking areas as non-walkable.

Demonstrated in custom areas storybook:

• https://github.com/isaac-mason/recast-navigation-js/blob/main/packages/recast-navigation/.storybook/stories/advanced/custom-areas-generator.ts
• https://github.com/isaac-mason/recast-navigation-js/blob/main/packages/recast-navigation/.storybook/stories/advanced/custom-areas.stories.tsx
• https://recast-navigation-js.isaacmason.com/?path=/story/advanced-custom-areas--compute-path