Feat: Add is admin utility

[Asartea]

Because

• We currently duplicate this code

This PR

• Adds an isAdmin(member) utility
• Replace all code that did this previously with usages of the new function
• Fixes using Map() for mocking in points.test.js to use Collection() instead
• Runs prettier over all affected files

Issue

Closes #566

Pull Request Requirements

• I have thoroughly read and understand The Odin Project Contributing Guide
  - [] The title of this PR follows the location of change: brief description of change format, e.g. Callbacks command: Update verbiage
• The Because section summarizes the reason for this PR
• The This PR section has a bullet point list describing the changes in this PR
• If this PR addresses an open issue, it is linked in the Issue section
• If this PR adds new features or functionality, I have added new tests
• If applicable, I have ensured all tests related to any command files included in this PR pass, and/or all snapshots are up to date

[MaoShizhong]

Awesome work!

Further to the two points below, we also don't actually need the @discordjs/collection package. discord.js already exports Collection (which comes from their utility package), so we can just destructure Collection from the import, then when mocking 'discord.js', just have ...jest.requireActual('discord.js'), before our mocked properties.

e.g.

jest.mock('discord.js', () => ({
  ...jest.requireActual('discord.js'),
  Member: jest.fn().mockImplementation((roles) => ({
    roles: {
      cache: roles,
    },
  })),
}));

And the equivalent for points.test.js

[Asartea]

✅ Done

[MaoShizhong]

Very much a nit, but mind renaming any memberMap variables in both test files to memberCollection?
Once that's done, the rest looks good to me! 🙏

[Asartea]

✅

[MaoShizhong]

I didn't even realise I didn't formally approve. Well that's something to address.