Unneeded wildcard imporvement

[jcarey9149]

changelog: [unneeded_wildcard_pattern]: add support for struct constructs.

The existing lint only looks at tuples and tuplestructs. This change adds support for standard structs, looking for cases
where one or more _ immediately preceed a ... The preceeding _ members may be omitted, as they will be collected by the .. operator.

[rustbot]

r? @llogiq

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The reviewer was selected based on:

• Owners of files modified in this PR: 7 candidates
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• Random selection from Jarcho, dswij, llogiq, samueltardieu

[jcarey9149]

@rustbot ready

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.