core(fr): add navigations to config

[patrickhulce]

Summary
Adds basic navigations to the fraggle rock config. I decided to go ahead and document the complete navigation config object so everyone can see where it's headed and what replaces what even if the properties aren't supported in the navigation prototype yet (see config.d.ts).

Fraggle Rock Config

const configJson = {
    artifacts: [{id: 'Accessibility', gatherer: 'accessibility'}],
    navigations: [{id: 'default', artifacts: ['Accessibility']}],
};

Legacy Config

const configJson = {
    passes: [{passName: 'defaultPass', gatherers: ['accessibility']}],
};

Related Issues/PRs
ref #11313
design doc