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This change brings in the basic pace plans frontend with
styled-components and several other smaller libraries replaced with
InstUI 7 components. It also adds the 'reselect' library as a direct
dependency (which we already had through @instructure/outcomes-ui) and
'tsc-files' for type-checking of staged TS files on commit. There were
also some tweaks to typescript and eslint configs, mostly to get both
up to speed with the typescript code.

Finally, this also adds a `pace_plans` endpoint to
`courses_controller` to bootstrap the frontend-- this will get moved
to `pace_plans_controller` once it has been merged.

It's also worth noting that no frontend tests are included with this
change-- the existing tests were written with enzyme and are heavily
snapshot-based, so we will be replacing those with
@testing-library/react tests in later updates (in keeping with current
testing best practices at Instructure).

closes LS-2431, LS-2432, LS-2433, LS-2434, LS-2452
flag = pace_plans

Test ...