Investigate using simd-json for performance improvements

[rtyler]

In production 🌭 is typically CPU bound on JSON parsing, JSON serialization, and Handlebars template rendering.

simd-json might be a good route to explore for enabling for platforms that support SIMD.

[rtyler]

At first glance it looks like simd-json is not API compatible with serde, since its from_str and from_slice methods will actually consume the buffer 🤦

   Compiling hotdog v0.3.3 (/home/tyler/source/github/reiseburo/hotdog)
error[E0308]: mismatched types
  --> src/json.rs:15:41
   |
15 |         simd_json::serde::from_str::<S>(buffer)
   |                                         ^^^^^^ types differ in mutability
   |
   = note: expected mutable reference `&mut str`
                      found reference `&'a str`

error[E0308]: mismatched types
  --> src/json.rs:15:9
   |
12 | pub fn from_str<'a, S: serde::Deserialize<'a>>(buffer: &'a str) -> Result<S, serde_json::error::Error> {
   |                                                                    ----------------------------------- expected `std::result::Result<S, serde_json::error::Error>` because of return type
...
15 |         simd_json::serde::from_str::<S>(buffer)
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected struct `serde_json::error::Error`, found struct `simd_json::Error`
   |
   = note: expected enum `std::result::Result<_, serde_json::error::Error>`
              found enum `std::result::Result<_, simd_json::Error>`

error: aborting due to 2 previous errors

[rtyler]

Work going on in the simd branch