feat(view-hierarchy): Allow forcing absolute positioning

[timfish]

• Ref feat: Add positioning: "relative|absolute" to View Hierarchy rfcs#150
• cc @Lms24

Currently relative/absolute positioning for View Hierarchy wireframes is always relative unless the platform matches a predefined list:

sentry/static/app/components/events/viewHierarchy/wireframe.tsx

Lines 51 to 54 in e07092c

	getHierarchyDimensions(
	hierarchy,
	['flutter', 'dart-flutter'].includes(platform ?? '')
	),

This PR allows overriding the platform defaults via the root positioning property in the hierarchy data.

[timfish]

I think the CI failures are related to permissions because this is on my fork. Let me know if you want me to push this to the Sentry repo (if I have permissions!).

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