ref(dev): Add dev-utils package

[lobsterkatie]

Since we're not using it immediately, I'm going to wait to merge this until a few other structural changes have gone through. Moving back to draft.

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This adds the skeleton of a new dev-utils package, which will eventually hold a lot of the stuff that's started to litter the top level of our repo (rollup helpers, jest transformers, etc), as well as give us a place to put, for example, testing helpers which right now have to be copied across packages.

Work to move things into the package (and update anything that points to the old locations) will happen in follow-up PRs.

Note: There is a little cruft here, of the kind from which all of our packages suffer, which I left alone (for the moment) for simplicity's sake. When we do the work to clean up this junk repo-wide, these crufty areas will get taken care of.

[Lms24]

I think it's a good change to have this extra package. I left some questions/comments but they shouldn't block for now, given that the package itself is still empty. Seems like building the package fails in CI though. I think if we fix CI, this is good to go from my perspective.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	18.78 KB (-6.77% 🔽)
@sentry/browser - ES5 CDN Bundle (minified)	58.38 KB (-9.65% 🔽)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	17.54 KB (-7% 🔽)
@sentry/browser - ES6 CDN Bundle (minified)	52.61 KB (-9.26% 🔽)
@sentry/browser - Webpack (gzipped + minified)	19.33 KB (-16.83% 🔽)
@sentry/browser - Webpack (minified)	61.47 KB (-24.77% 🔽)
@sentry/react - Webpack (gzipped + minified)	19.35 KB (-16.87% 🔽)
@sentry/nextjs Client - Webpack (gzipped + minified)	42.81 KB (-10.91% 🔽)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	24.43 KB (-6.3% 🔽)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	23 KB (-6.05% 🔽)

[github-actions]

This pull request has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you label it Status: Backlog or Status: In Progress, I will leave it alone ... forever!

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"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀

[AbhiPrasad]

This is a great idea we should pursue later on, but for now closing.