Rename rustdoc lints to be a tool lint instead of built-in.

- Rename `broken_intra_doc_links` to `rustdoc::broken_intra_doc_links`
- Ensure that the old lint names still work and give deprecation errors
- Register lints even when running doctests

  Otherwise, all `rustdoc::` lints would be ignored.

- Register all existing lints as removed

  This unfortunately doesn't work with `register_renamed` because tool
  lints have not yet been registered when rustc is running. For similar
  reasons, `check_backwards_compat` doesn't work either. Call
  `register_removed` directly instead.

- Fix fallout

  + Rustdoc lints for compiler/
  + Rustdoc lints for library/

Note that this does *not* suggest `rustdoc::broken_intra_doc_links` for
`rustdoc::intra_doc_link_resolution_failure`, since there was no time
when the latter was valid.

compiler/rustc_ast/src/attr/mod.rs

@@ -34,7 +34,7 @@ impl MarkedAttrs {
 }
 
 pub fn is_known_lint_tool(m_item: Ident) -> bool {
-    [sym::clippy, sym::rustc].contains(&m_item.name)
+    [sym::clippy, sym::rustc, sym::rustdoc].contains(&m_item.name)
 }
 
 impl NestedMetaItem {