memory dump file preview

Add a preview for .NET `gcdump` files:

The preview tool for web is here:
[https://github.com/getsentry/dotnet-heapview]()

Docs for the feature are landing here:

* [https://github.com/getsentry/sentry-docs/pull/12848]()

Example event: [https://sentry.sentry.io/issues/6336223012/?project=1886021&query=is%3Aunresolved issue.priority%3A\[high%2C medium\]&referrer=issue-stream&sort=date&statsPeriod=24h&stream_index=0]()

Note: The preview component has to be loaded only if an event with this specific attachment type is available, and someone clicks `Preview`. Since the preview tool can be quite large.

Start with the dotnet-heapview web preview tool and the example event linked in the issue, then review the Preview flow for the specific attachment type. The feature is done when gcdump attachments can be previewed on demand and the preview component is not loaded for other events or before Preview is clicked.

Written by the indexing model from the issue text.