Leaderboard refactor

[sayomaki]

Description

• Updated endpoints and requests to match updated backend routes
• Directly call requests for exporting of leaderboard instead of using store
• Remove toggles and fields for leaderboard during course creation
• Only show leaderboard in contest assessment workspace after assessment is published
• Combined contest leaderboard may not work as expected due to breaking changes (need to disable contest leaderboard for now)

This PR is an improvement on #3113

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Code quality improvements

How to test

Requires backend PR: source-academy/backend#1281

Possible planned improvements (not in PR)

• Consider feasibility of keeping overall contest leaderboards, improve design if keeping
• Improve achievements system and incorporate achievements with leaderboards
• Combined contest leaderboards should be retrieved directly from assessment instead of additional endpoint
• QoL improvements to voting features and token counter

[coveralls]

Pull Request Test Coverage Report for Build 16802172057

Details

• 8 of 82 (9.76%) changed or added relevant lines in 7 files are covered.
• 7 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.07%) to 43.392%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/commons/sagas/LeaderboardSaga.ts	1	3	33.33%
src/pages/leaderboard/subcomponents/OverallLeaderboard.tsx	0	2	0.0%
src/commons/sagas/RequestsSaga.ts	2	19	10.53%
src/commons/assessmentWorkspace/AssessmentWorkspace.tsx	2	25	8.0%
src/pages/leaderboard/subcomponents/LeaderboardExportButton.tsx	0	30	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/pages/leaderboard/subcomponents/OverallLeaderboard.tsx	1	0.0%
src/commons/sideContent/content/SideContentContestLeaderboard.tsx	6	83.75%

Totals
Change from base Build 16799186972:	-0.07%
Covered Lines:	20441
Relevant Lines:	49284

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💛 - Coveralls

[RichDom2185]

Just some minor nits :)

[RichDom2185]

LGTM, thanks!