build: add swift-format plugins

[kkebo]

No description provided.

[kkebo]

This PR slows down the CI workflows because the package Benchmarks is built. So I don't merge it.

• 8m 48s https://github.com/kkk669/zyphy/actions/runs/6382772173
• 12m 29s https://github.com/kkk669/zyphy/actions/runs/6394133067

[kkebo]

#19 may resolve #14 (comment).

[kkebo]

• before (without caches): 8m 59s
• before (with caches): 2m 0s
• after (without caches): 14m 37s
• after (with caches): 2m 33s

[kkebo]

• before (without caches): 8m 59s
• before (with caches): 2m 0s
• after (without caches): 14m 37s
• after (with caches): 2m 33s

If swift package --package-path Benchmarks lint-source-code is removed, the time of "after" is as fast as the one of "before". Originally, the Benchmarks package was not built on GitHub Actions, so it's almost the same behavior if I remove that line.