move CSP definition to central file

We want to be sure we define (and potentially change) this only once

Remove the SVG Sanitizer again in favor of CSP headers

This introduces a renderer that allows us to call each embedded SVG as a
separate URL with added CSP headers. This way we rely on the same safe

Remove the SVG Sanitizer again in favor of CSP headers

This introduces a renderer that allows us to call each embedded SVG as a
separate URL with added CSP headers. This way we rely on the same safety
feature as with media file based diagrams.

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