Bump ejs and @open-wc/building-rollup in /webconnector/frontend

Bumps [ejs](https://github.com/mde/ejs) and [@open-wc/building-rollup](https://github.com/open-wc/open-wc/tree/HEAD/packages/building-rollup). These dependencies needed to be updated together.

Updates `ejs` from 2.7.4 to 3.1.8
- [Release notes](https://github.com/mde/ejs/releases)
- [Changelog](https://github.com/mde/ejs/blob/main/CHANGELOG.md)
- [Commits](mde/ejs@v2.7.4...v3.1.8)

Updates `@open-wc/building-rollup` from 1.10.0 to 2.0.2
- [Release notes](https://github.com/open-wc/open-wc/releases)
- [Changelog](https://github.com/open-wc/open-wc/blob/master/packages/building-rollup/CHANGELOG.md)
- [Commits](https://github.com/open-wc/open-wc/commits/@open-wc/[email protected]/packages/building-rollup)

---
updated-dependencies:
- dependency-name: ejs
  dependency-type: indirect
- dependency-name: "@open-wc/building-rollup"
  dependency-type: direct:development
...

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