chore(deps): remove unused `antd` directory and deps

[agilgur5]

Per https://github.com/argoproj/argo-ui/issues/553#issuecomment-2106048778 and https://github.com/argoproj/argo-ui/issues/453#issuecomment-2106051851, remove the unused antd dir and deps

• antd was seemingly meant to be used in v2 per https://github.com/argoproj/argo-ui/pull/161#pullrequestreview-820560829, but that never happened.
  • It's been ~2.5 years since and per #453 this repo is effectively deprecated & unmaintained. Moving forward, Argoproj UIs should use antd directly instead of argo-ui, as Rollouts is doing in some places

Motivation

• there are no components, only stories in the ./antd dir
  • and doubly confirmed that none of these are used in CD, Workflows, or Rollouts

Modifications

• so remove the ./antd dir entirely as well as all related deps
  • antd ofc, but also all the less deps and the gulp build for antd's styles
    • I'm not even sure what the gulp build was for exactly, nor why it used different tooling than already existed in this repo

Verification

The removed files etc are entirely unused

[agilgur5]

Fixed merge conflict with #534

[agilgur5]

Fixed a tiny merge conflict in the package.json#scripts from #536