Auto merge of #9541 - Alexendoo:declare-proc-macro, r=flip1995

Generate lint categories and explanations with `declare_clippy_lint`

This means contributors will no longer have to run `cargo dev update_lints` after changing a lints documentation or its category, which may also mean fewer merge conflicts in general

It works by swapping `declare_clippy_lint` out for a `proc_macro` of the same name. The proc macro emits a `LintInfo` alongside the generated `Lint` which are gathered into `declared_lint::LINTS`. The categories/explanations are then read from `declared_lint::LINTS` at runtime

The removal of `src/docs` is split into a separate commit to be more easily ignored

It is slightly slower though, adding a bit under a second to build time. Less noticeable in full builds or with a slower linker (benchmark uses mold)

```bash
hyperfine --warmup 2 \
    --parameter-list commit "declare-proc-macro,master" \
    --command-name "{commit}" \
    --setup "git checkout {commit}" \
    --prepare "touch clippy_lints/src/lib.rs" \
    "cargo build"
```
```
Benchmark 1: declare-proc-macro
  Time (mean ± σ):     10.731 s ±  0.154 s    [User: 7.739 s, System: 1.791 s]
  Range (min … max):   10.598 s … 11.125 s    10 runs

Benchmark 2: master
  Time (mean ± σ):      9.422 s ±  0.094 s    [User: 7.183 s, System: 1.732 s]
  Range (min … max):    9.287 s …  9.624 s    10 runs

Summary
  'master' ran
    1.14 ± 0.02 times faster than 'declare-proc-macro'
```

r? `@flip1995`
cc `@llogiq` for `--explain`

changelog: none

1 files changed, 0 insertions, 32 deletions

diff --git a/src/docs/linkedlist.txt b/src/docs/linkedlist.txt
deleted file mode 100644
index 986ff1369e3..00000000000
--- a/src/docs/linkedlist.txt
+++ /dev/null
@@ -1,32 +0,0 @@
-### What it does
-Checks for usage of any `LinkedList`, suggesting to use a
-`Vec` or a `VecDeque` (formerly called `RingBuf`).
-
-### Why is this bad?
-Gankro says:
-
-> The TL;DR of `LinkedList` is that it's built on a massive amount of
-pointers and indirection.
-> It wastes memory, it has terrible cache locality, and is all-around slow.
-`RingBuf`, while
-> "only" amortized for push/pop, should be faster in the general case for
-almost every possible
-> workload, and isn't even amortized at all if you can predict the capacity
-you need.
->
-> `LinkedList`s are only really good if you're doing a lot of merging or
-splitting of lists.
-> This is because they can just mangle some pointers instead of actually
-copying the data. Even
-> if you're doing a lot of insertion in the middle of the list, `RingBuf`
-can still be better
-> because of how expensive it is to seek to the middle of a `LinkedList`.
-
-### Known problems
-False positives – the instances where using a
-`LinkedList` makes sense are few and far between, but they can still happen.
-
-### Example
-```
-let x: LinkedList<usize> = LinkedList::new();
-```
\ No newline at end of file