feat: Support exactOptionalPropertyTypes on ErrorBoundary

[quisido]

TypeScript has a exactOptionalPropertyTypes flag that uses stricter typing on objects.

type T = { property?: V } means T['property'] V or !('property' in T), but T['property'] cannot === undefined.

This means that consumers of @sentry/react who have exactOptionalPropertyTypes enabled cannot set an ErrorBoundary prop to undefined without hard-failing TypeScript transpilation.

This PR attempts to fix that.

[getsantry]

This issue 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 remove the label Waiting for: Community, I will leave it alone ... forever!

---

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

[quisido]

Please review 🙏

[quisido]

@HazAT @lforst What is the process for getting a PR reviewed?

[lforst]

Sorry, this slipped through. We don't have proper channels in place for community PRs and we need to improve this.

I will look at this PR this week in a sec!

[quisido]

@lforst Thank you. I rebased through the PR UI. Hopefully it's mergeable soon.

[lforst]

Thank you!