…aumeGomez

Replace `check_missing_items.py` with `jsondoclint`

[zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/266220-rustdoc/topic/check_missing_items.2Epy.20Replacement.2E)

check_missing_items.py was a python script that checked rustdoc json output to make sure all the Id's referenced existed in the JSON index. This PR replaces that with a rust binary (`jsondoclint`) that does the same thing.

### Motivation

1. Easier to change when `rustdoc-json-types` changes, as `jsondoclint` uses the types directly.
2. Better Errors:
    - Multiple Errors can be emited for a single crate
    - Errors can say where in JSON they occored
        ```
        2:2889:408 not in index or paths, but refered to at '.index."2:2888:104".inner.items[0]'
        2:2890:410 not in index or paths, but refered to at '.index."2:2888:104".inner.items[1]'
        ```
3. Catches more bugs.
    - Because matches are exaustive, all posible variants considered for enums
    - All Id's checked
    - Has already found rust-lang#101770, rust-lang#101199 and rust-lang#100973
    - Id type is also checked, so the Id's in a structs fields can only be field items.
4. Allows the possibility of running from `rustdoc::json`, which we should do in a crator run at some point.

cc `@CraftSpider`

r? `@GuillaumeGomez`

…aumeGomez

Replace `check_missing_items.py` with `jsondoclint`

[zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/266220-rustdoc/topic/check_missing_items.2Epy.20Replacement.2E)

check_missing_items.py was a python script that checked rustdoc json output to make sure all the Id's referenced existed in the JSON index. This PR replaces that with a rust binary (`jsondoclint`) that does the same thing.

### Motivation

1. Easier to change when `rustdoc-json-types` changes, as `jsondoclint` uses the types directly.
2. Better Errors:
    - Multiple Errors can be emited for a single crate
    - Errors can say where in JSON they occored
        ```
        2:2889:408 not in index or paths, but refered to at '.index."2:2888:104".inner.items[0]'
        2:2890:410 not in index or paths, but refered to at '.index."2:2888:104".inner.items[1]'
        ```
3. Catches more bugs.
    - Because matches are exaustive, all posible variants considered for enums
    - All Id's checked
    - Has already found rust-lang#101770, rust-lang#101199 and rust-lang#100973
    - Id type is also checked, so the Id's in a structs fields can only be field items.
4. Allows the possibility of running from `rustdoc::json`, which we should do in a crator run at some point.

cc `@CraftSpider`

r? `@GuillaumeGomez`

Rollup of 7 pull requests

Successful merges:

 - rust-lang#101722 (Rustdoc-Json: Fix Type docs.)
 - rust-lang#101738 (Fix `#[link kind="raw-dylib"]` to respect `#[link_name]`)
 - rust-lang#101753 (Prefer explict closure sig types over expected ones)
 - rust-lang#101787 (cache `collect_trait_impl_trait_tys`)
 - rust-lang#101802 (Constify impl Fn* &(mut) Fn*)
 - rust-lang#101809 (Replace `check_missing_items.py` with `jsondoclint`)
 - rust-lang#101864 (rustdoc: remove no-op CSS `h1-4 { color: --main-color }`)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup