Fix contxt types for Route.LoaderArgs, add upgrade docs

[brophdawg11]

• Remove optional context from Route.ClientLoaderArgs/Route.ClientActionArgs
• Make context non-optional in Route.LoaderArgs/Route.ActionArgs
• Add docs to the Remix v2 upgrade guide on how to use module augmentation to properly type LoaderFunctionArgs/ActionFunctionArgs for the migration

[changeset-bot]

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Latest commit: e94409a

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