chore: stricter deprecation for layout.spring() and layout.svd()

[maelle]

This was validated by @szhorvat and @ntamas in #685 but @krlmlr we might want to see whether it creates revdeps failures.

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[maelle]

mmmh a few use cases in https://github.com/search?q=layout.spring%28+language%3AR+owner%3Acran+NOT+repo%3Acran%2Figraph+path%3A%2F%5ER%5C%2F%2F+NOT+repo%3Acran%2Figraph0&type=code&ref=advsearch

[maelle]

and https://github.com/search?q=layout.svd%28+language%3AR+owner%3Acran+NOT+repo%3Acran%2Figraph+path%3A%2F%5ER%5C%2F%2F+NOT+repo%3Acran%2Figraph0&type=code&ref=advsearch

[szhorvat]

@krlmlr Should this be included in 2.2.0 and in revdepchecks?

[krlmlr]

We discussed with Maëlle, let's give it another couple of years.

[maelle]

Or months 😇 Should I close this in the meantime?

[krlmlr]

Why would you close it? Draft PRs are fine.