[Rust APIView] Builder method is rendered with `&self` instead of consuming `self`

Bad code snippet:
```Rust
pub fn with_indexing_policy(&self, indexing_policy: IndexingPolicy) -> Self {}
```

What it should do:
The APIView rendering is misrepresenting the method signature. This is a parser/rendering bug and should be corrected so the code is displayed accurately.

Good code snippet:
```Rust
pub fn with_indexing_policy(mut self, indexing_policy: IndexingPolicy) -> Self {}
```

Start by locating the Rust APIView parser and renderer entry points responsible for method receivers. Compare how the bad `&self` signature and the expected consuming `self` signature are parsed and rendered. Done means the `with_indexing_policy` example is displayed with `mut self` as shown in the issue.

Written by the indexing model from the issue text.