Implement assessment card why view

Feature Merge Request

Related Issue

relates to #371 (closed)

Motivation and Context

Assessment Cards have a why button, they should trigger a new Card view, with an explanation, depending on the context.

Implementation

• Use a local state variable to let the user toggle a toggleWhy variable and replace the regular assessmentCard content with an explanation

• modify linkButtons so that why is also displayed for current assessments and that the explanationCard gets the specific stage

• Leave the actual content for later

Next

• Do the same for concepts (#391 (closed))
• Implement global explanationCard component https://gitlab.com/fathom/app/issues/392
• Write relevant text for each case
• Apply similar modification to concept cards

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