Generate lint categories and explanations with declare_clippy_lint

Changes it to be a proc_macro rather than macro_rules

Author: Alexendoo

clippy_dev/src/update_lints.rs

@@ -11,6 +11,7 @@ edition = "2021"
 [dependencies]
 cargo_metadata = "0.14"
 clippy_utils = { path = "../clippy_utils" }
+declare_clippy_lint = { path = "../declare_clippy_lint" }
 if_chain = "1.0"
 itertools = "0.10.1"
 pulldown-cmark = { version = "0.9", default-features = false }