fix(material/icon): keep FuncIRI references on current origin

[moamenmahmod]

Summary

• keep MatIcon FuncIRI rewrites on the current origin when the page path starts with //
• preserve the exact multi-slash current-document path by making it explicitly root-relative with a
  dot segment
• add a regression test covering multiple leading slashes, a path, and a query string

Background

MatIcon._prependPathToReferences() prepends the current pathname and search string to SVG
same-document references. A pathname beginning with // is otherwise parsed as a protocol-relative
URL, which can turn url(#id) into a cross-origin request.

Google's OSS VRP referred this report to the Angular maintainers as issue 548479960.
The local-only browser reproduction and evidence are available at
https://github.com/moamenmahmod/angular-material-funciri-poc.

Fixes #33811

Testing

• pnpm test src/material/icon --no-watch
• pnpm lint

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