Add duplicate modules conflict

[ChillinRage]

Duplicate conflict checks if there are modules with the same module code added to the same academic year and semester.

Context

Proposal to fix #3732 which having same modules in the same year/semester shows no warnings.

Implementation

Added a new conflict that checks if the module list for a given semester has more than one module of the same module code.

Other Information

Added test case for the conflict, though I'm slightly confused as to what's the role/difference between planner and moduleBank (the variables in the planner.test.ts)?

[vercel[bot]]

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Name	Status	Preview	Comments	Updated (UTC)
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[vercel[bot]]

@ChillinRage is attempting to deploy a commit to the modsbot's projects Team on Vercel.

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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.

Project coverage is 53.63%. Comparing base (e6423d8) to head (6efddc3).

Files	Patch %	Lines
website/src/views/planner/PlannerModule.tsx	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #3738 +/- ## ========================================== + Coverage 53.60% 53.63% +0.02% ========================================== Files 274 274 Lines 6025 6032 +7 Branches 1446 1449 +3 ========================================== + Hits 3230 3235 +5 - Misses 2795 2797 +2 ```

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[ChillinRage]

Apologies for the missing message and late response too. I've added the section that should display a warning message. Is there a way in which I can run a live webpage that allows me to test my local changes?

[ravern]

Apologies for the missing message and late response too. I've added the section that should display a warning message. Is there a way in which I can run a live webpage that allows me to test my local changes?

Yes! Once you've cloned the repository, just run cd website to enter the website folder, yarn install to install all the dependencies, and then yarn start to start the web server.

Let me know if that works.

[ChillinRage]

Yes I just tried yarn start and it works. Thank you!

As for the conflict message, it does appear after the changes.