[DOC] Add missing YUIDoc tags for @ember/helper exports

[crazylogic03]

Resolves #20153. Adding missing @method, @for, @public, and @static tags for array, concat, fn, get, hash, and uniqueId in @ember/helper/index.ts so they appear in the documentation.

[crazylogic03]

Hey @NullVoxPopuli !

The Linting CI job was failing earlier because Ember's custom lint:docs test enforces strict tracking of all exported documentations. Since my previous commit added YUIDoc tags for uniqueId, the docs generator picked it up as a new public API item, which caused the coverage test to flag it as "extraneous" because it wasn't listed in the expected output.

I have pushed a new commit to add uniqueId to

tests/docs/expected.js
to satisfy the coverage expectation. The npm run lint:docs check now passes perfectly locally, so this PR is clean, green, and ready for review whenever you have a moment! Thanks!

[NullVoxPopuli]

@kategengler I think this PR would fix this page, where most of the exports are missing, ya? https://api.emberjs.com/ember/release/modules/@ember%2Fhelper

[kategengler]

I need to check the end result of this being deployed. There are some particularities of the docs set up that mean it may not go where it is supposed to go.