Comply with rust-lang/rfcs#2140

[eclairevoyant]

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Description

Renames drain_filter to extract_if and hash_drain_filter to hash_extract_if as per rust-lang/rfcs#2140. Fixes #810 and #841.

Usage

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Showcase

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Additional Notes

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Checklist

Please make sure you can check all the boxes that apply to this PR.

• All widgets I've added are correctly documented.
• I added my changes to CHANGELOG.md, if appropriate.
• The documentation in the docs/content/main directory has been adjusted to reflect my changes.
• I used cargo fmt to automatically format all code before committing

[bal-e]

Not a maintainer, but thanks for making the PR, because I hit the same issue. I tried compiling your branch myself, and I noticed a funny warning in crates/eww/src/error_handling_ctx.rs (line 56): the iterator resulting from extract_if() isn't being used. I think that it's a bug - the correct intention was to remove all the matching items, and this should instead be done with Vec::retain() (this is also mentioned in the documentation for Vec::extract_if()). Can somebody confirm that this is a bug, and if so, can this PR be updated to solve it?

[eclairevoyant]

A warning is not a "bug" but I've updated it nonetheless.