Rust: Render 64-bit and larger integers as strings in JSON

[leighmcculloch]

What

Render 64-bit integers as strings in JSON.

Why

JS runtimes cannot correctly decode JSON numbers greater than 53-bits.

[leighmcculloch]

Given that so many tools support 64-bit integers in JSON I'm thinking maybe we should follow a pattern I've heard folks using, where the 64-bit integer is encoded into two fields, in a number in a field by it's native name, and in a string in a field by its native name suffixed with _str.

For example:

{
    "my_field": 1,
    "my_field_str": "1",
    // ...

The downside of this is that someone may still use the my_field in JS and unknowingly be interpreting the JSON data as a Number with lost precision.