fix: invalid date formatting on course route

[adamstankiewicz]

Description

Resolves "Invalid Date" messages on course about page in Learner Portal in Firefox (appears fine in Chrome). The error seems to be due to different browsers' parsing/handling of datetime strings.

Locally, there was a JS error triggers by react-intl's FormattedDate component:

Error: [@formatjs/intl Error FORMAT_ERROR] Error formatting date.
Locale: en
date value is not finite in DateTimeFormat.format()

The solution was to ensure the raw date string was passed to FormattedDate vs. passing the already-formatted date via dayjs(...).format(DATE_FORMAT).

This PR also switches to use getNormalizedStartDate within the deprecated CourseRunCard component to ensure today's date is used for display, where relevant (i.e., self-paced courses with time-to-complete).

For all changes

• Ensure adequate tests are in place (or reviewed existing tests cover changes)
• Ensure English strings are marked for translation. See documentation for more details.

Only if submitting a visual change

• Ensure to attach screenshots
• Ensure to have UX team confirm screenshots

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.85%. Comparing base (01c8a57) to head (6a32dce).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1233      +/-   ##
==========================================
- Coverage   88.88%   88.85%   -0.04%     
==========================================
  Files         401      401              
  Lines        8595     8595              
  Branches     2060     2060              
==========================================
- Hits         7640     7637       -3     
- Misses        913      916       +3     
  Partials       42       42              

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