Fix out of memory file upload of 2gb+ files introduced by #14657 SVG xss

[TimBoonstra]

According to the v13 docs you can set the max filesize using maxAllowedContentLength to 4GB, however when you drag/drop a 2gb+ file in the media library it will throw an out of memory error.

This bug was introduced with the security SVG XSS hotfix #14657 by using a MemoryStream which has a max size of 2GB instead of the FileStream which does allow for 4GB files.

[github-actions]

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[mikecp]

Hello @TimBoonstra,

Thanks for spotting the issue and providing the fix! 👍🤩
A member of the core collaborators team will have a look at it soon.

I see this is your first PR to the Umbraco repository, congratulations 😉 !!
If you have an account on Our.umbraco.com, please mention it here so that we can assign your contributor badge once your PR will be merged 😁

Cheers!