Rename lint identity_conversion to useless_conversion

[ThibsG]

Lint name identity_conversion was misleading, so this PR renames it to useless_conversion.

As decision has not really came up in the issue comments, this PR will probably need discussion.

fixes #3106

changelog: Rename lint identity_conversion to useless_conversion

[flip1995]

For renaming lints the lint has to be store.register_renamed(..). Otherwise approved.

[flip1995]

@bors r+

Thanks!

[bors]

📌 Commit 344ecdf has been approved by flip1995

[bors]

⌛ Testing commit 344ecdf with merge 5fa247a...

[flip1995]

@bors retry (prio the mass renaming PR)

[bors]

🔒 Merge conflict

This pull request and the master branch diverged in a way that cannot be automatically merged. Please rebase on top of the latest master branch, and let the reviewer approve again.

How do I rebase?

Assuming self is your fork and upstream is this repository, you can resolve the conflict following these steps:

1. git checkout RenameIdentityConversionLint (switch to your branch)
2. git fetch upstream master (retrieve the latest master)
3. git rebase upstream/master -p (rebase on top of it)
4. Follow the on-screen instruction to resolve conflicts (check git status if you got lost).
5. git push self RenameIdentityConversionLint --force-with-lease (update this PR)

You may also read Git Rebasing to Resolve Conflicts by Drew Blessing for a short tutorial.

Please avoid the "Resolve conflicts" button on GitHub. It uses git merge instead of git rebase which makes the PR commit history more difficult to read.

Sometimes step 4 will complete without asking for resolution. This is usually due to difference between how Cargo.lock conflict is handled during merge and rebase. This is normal, and you should still perform step 5 to update this PR.

Error message

Auto-merging tests/ui/useless_conversion.stderr
Auto-merging tests/ui/useless_conversion.rs
Auto-merging tests/ui/useless_conversion.fixed
Auto-merging src/lintlist/mod.rs
Auto-merging clippy_lints/src/useless_conversion.rs
Auto-merging clippy_lints/src/lib.rs
CONFLICT (content): Merge conflict in clippy_lints/src/lib.rs
Auto-merging CHANGELOG.md
Automatic merge failed; fix conflicts and then commit the result.

[bors]

☔ The latest upstream changes (presumably #5563) made this pull request unmergeable. Please resolve the merge conflicts.

[flip1995]

You can ping me after rebase to re-approve. 👍

[flip1995]

@bors r+

[bors]

📌 Commit e55b920 has been approved by flip1995

[bors]

⌛ Testing commit e55b920 with merge 9e839b5...

[bors]

💔 Test failed - checks-action_test

[flip1995]

Don't worry about the test failure. This is already fixed in #5608

[phansch]

@bors retry

[bors]

⌛ Testing commit e55b920 with merge 5eff742...

[bors]

💔 Test failed - checks-action_remark_test

[phansch]

@bors retry (not sure what went wrong with the remark build)

[bors]

⌛ Testing commit e55b920 with merge e214ea8...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: flip1995
Pushing e214ea8 to master...