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.

src/test/rustdoc-ui/lint-missing-doc-code-example.stderr

@@ -8,8 +8,8 @@ LL | | }
 note: the lint level is defined here
   --> $DIR/lint-missing-doc-code-example.rs:2:9
    |
-LL | #![deny(missing_doc_code_examples)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | #![deny(rustdoc::missing_doc_code_examples)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: missing code example in this documentation
   --> $DIR/lint-missing-doc-code-example.rs:37:3