Feature: Strongly typed deserialization of JSON ops

[jbellerb]

I've been messing with deno_core a bit and I found it a bit strange that JSON ops only work on loosely typed serde_json::Values given serde is capable of directly converting between JSON and Rust types. This can be changed by simply updating the type signatures of json_op_sync/async. Since serde_json::Value implements Deserialize/Serialize, very little code needs to be changed, however as json_op_sync/async are now generic, type inference is broken in some cases (see cli/build.rs:146).

Since the changes required for this feature are so simple, I've made them on a fork of deno (which can be upgraded to a PR if there is interest) for testing. I've also updated the deno_core examples and found that this change removed a lot of boilerplate. Finally, since serde now has more information about the types it is working with, serialization and deserialization should be faster, but I don't have benchmarks to back up that claim. Is there any interest in making this change? Thanks.

[lucacasonato]

Please open a PR to discuss this further. Sounds interesting - benchmarks would be nice.

[jbellerb]

I've created a PR (#9423) . I'll try to get some basic benchmarks based on http_bench_json_ops soon.