feat(react-nav-preview): Flagship Nav example

[mltejera]

Adds styles for the nav component that will be turned into composed components and re-exported over the course of the next few weeks.

Adds the main nav story to the big kid story book.

Before:

After:

[fabricteam]

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[lydsmit]

Hello world!

[Hotell]

after running the initial release generator, I'd suggest to do that in separate PR as it's not a good practice to combine adding features with initial release.

tip: also please use github re-request review next time if you submitted changes based on the feedback, otherwise it wont show in peoples github inbox , thus will not be able to look it up.

[mltejera]

after running the initial release generator, I'd suggest to do that in separate PR as it's not a good practice to combine adding features with initial release.

tip: also please use github re-request review next time if you submitted changes based on the feedback, otherwise it wont show in peoples github inbox , thus will not be able to look it up.

Agreed that separation is good practice. I don't think I'm adding any features in this PR though? Just doing some pixel pushing and creating a realistic example.