Splitting `unnecessary_map_or` into 2 lints

[teofr]

Description

unnecessary_map_or is a bit of a complicated lint, #14713 suggested distilling part of its behaviour into a separate lint. That issue together with #15998 would split the behaviour entirely in two:

• For inequalities, it would lint the same cases x.map_or(true, |n| n > 5) but under a different name
• For equalities, x.map_or(false, |n| n == 5) it would first lint through manual_is_variant_and into x.is_some_and(|n| n == 5) and then through the lint in suggest == Some( for is_some_and if possible #14713 it would lint into x == Some(5)

After these things are done, I'd consider deprecating the lint all together.

Version

rustc 1.92.0-nightly (57ef8d642 2025-10-15)
binary: rustc
commit-hash: 57ef8d642d21965304bde849bab4f389b4353e27
commit-date: 2025-10-15
host: aarch64-apple-darwin
release: 1.92.0-nightly
LLVM version: 21.1.3

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