feat: fetch exams data on the progress page (#1829)

* feat: fetch exams data on the progress page

This commit adds changes to fetch the exams data associated with all subsections relevant to the progress page. Exams data is relevant to the progress page because the status of a learner's exam attempt may influence the state of their grade.

This allows children of the root ProgressPage or downstream plugin slots to access this data from the Redux store.

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Co-authored-by: nsprenkle <nsprenkle@2u.com>