Bump postcss and @angular-devkit/build-angular in /ui

Bumps [postcss](https://github.com/postcss/postcss) and [@angular-devkit/build-angular](https://github.com/angular/angular-cli). These dependencies needed to be updated together.

Updates `postcss` from 7.0.17 to 8.4.16
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@7.0.17...8.4.16)

Updates `@angular-devkit/build-angular` from 0.803.9 to 14.2.3
- [Release notes](https://github.com/angular/angular-cli/releases)
- [Changelog](https://github.com/angular/angular-cli/blob/main/CHANGELOG.md)
- [Commits](https://github.com/angular/angular-cli/commits/14.2.3)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: indirect
- dependency-name: "@angular-devkit/build-angular"
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>