fix(lint-configs): Suppress clang-tidy copy warnings for std::shared_ptr as the copy is necessary for reference counting.

[davidlion]

Description

The clang-tidy checks unnecessary-copy-initialization and unnecessary-value-param help devs to avoid unnecessary copies by pointing out when it is possible to use const&. This is great most of the time, but these checks will also flag reference counting types.

In our code this issue manifests primarily with std::shared_ptr function parameters. When the shared pointer would be copy constructed the reference count would be increased, however if the dev switches to std::shared_ptr const& there will be no reference counting as there is no construction. It is technically safe to do this as long as the object being referenced is guaranteed to not fall out of scope while the reference is held, but it is much easier to reason about reference counted types when they always perform the counting.
If performing these copies is ever a serious performance concern we should probably be investigating how to not use shared_ptrs entirely than skipping the copy.

There are other referencing counting stdlib types that this applies to, but I think we can add them on a case-by-case basis.

https://clang.llvm.org/extra/clang-tidy/checks/performance/unnecessary-copy-initialization.html
https://clang.llvm.org/extra/clang-tidy/checks/performance/unnecessary-value-param.html
llvm/llvm-project#153247

Checklist

• The PR satisfies the contribution guidelines.
• This is a breaking change and that has been indicated in the PR title, OR this isn't a
  breaking change.
• Necessary docs have been updated, OR no docs need to be updated.

Validation performed

I've been building y-scope/clp/main and davidlion/clp/clpp with these changes.

Summary by CodeRabbit

• Chores
  • Updated linting configuration to better handle reference-counted types in performance checks.
  • Allowed shared pointers in additional performance-related checks, with clearer guidance in the configuration comments.
  • Improved nearby comment punctuation for consistency.

[coderabbitai]

Walkthrough

The .clang-tidy config was updated to add std::shared_ptr allowlists for two performance checks and to adjust the surrounding comment text.

Changes

Lint configuration update

Layer / File(s)	Summary
Shared_ptr allowances exports/lint-configs/.clang-tidy	The existing public-member rule entry remains, its comment text is updated, and std::shared_ptr is allowed for performance-unnecessary-copy-initialization and performance-unnecessary-value-param.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title accurately describes the lint-config change to allow std::shared_ptr copies for clang-tidy warnings because reference counting requires the copy.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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