Add lint unnecessary_option_map_or_else

[pnuts93]

changelog: [unnecessary_option_map_or_else]: Added lint unnecessary_option_map_or_else. As suggested in the issue description, the implementation takes as reference the issue #7328. The tests for lints option_if_let_else and or_fun_call needed to be adjusted to comply with new lint.
fixes #14588

[rustbot]

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[llogiq]

This looks good in general, I just have a few subtle suggestions. Please use snippet_with_applicability instead of plain snippet. Otherwise, we end up breaking cargo fix. In addition, I'd like to see some tests for other scenarios.

[Jarcho]

Ping @pnuts93 this needs a rebase.

@llogiq is the review for this done?

[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.

[llogiq]

Yes, the review is done. r=me after a rebase.

[pnuts93]

Rebase is done