feat: display multifile projects (#45220)

* refactor: DRY up certification and ProjectModal

* fix: use sensible keys for SolutionViewer

* refactor: handle legacy solutions like new ones

* refactor: correct CompletedChallenge type

* fix: store challengeType for multifile projects

* fix: use challengeType to set display type

* feat: use dropdown to display project + code

* refactor: isOpen -> showCode to avoid a clash

We need to be able both show the code and show the completed project

* refactor: remove redundant parts of projectPreview

* refactor: fix project preview types

* feat: wip, using existing modal to show project

* feat: show projects on timeline

* feat: display projects on time-line

* chore: use consistent case for GitHub

* fix(a11y): translate show solution/view

* refactor: rename showFilesSolution

* refactor: use self-closing tag

* fix: remove hardcoding (certification + timeline)

* fix: remove hardcoding (settings)

* test: supply store and mock ga

* fix: include challengeType for projects

Co-authored-by: Tom <20648924+moT01@users.noreply.github.com>

* refactor: remove space

Co-authored-by: Tom <20648924+moT01@users.noreply.github.com>

* fix: key -> filekey on challenge submission

* fix: handle submissions without files

Co-authored-by: Tom <20648924+moT01@users.noreply.github.com>

client/i18n/locales/english/translations.json

@@ -8,6 +8,7 @@
     "edit": "Edit",
     "show-code": "Show Code",
     "show-solution": "Show Solution",
+    "show-project": "Show Project",
     "frontend": "Front End",
     "backend": "Back End",
     "view": "View",