…sponses (#1163)

<!-- The PR description should answer 2 important questions: -->

### What

Fixes:
https://linear.app/hasura/issue/ENG-1073/figure-out-whats-causing-the-slowdown-in-response-processing

This removes the accidentally-quadratic behavior of repeated
nested `from_value`/`to_value` calls where the assumption seems to have
been
that ndc model fields containing Value would be untouched (similar to
the behavior of aeson).

### How

We work with `Value` directly instead of using `serde` machinery to get
a `RowSet`.

#### Benchmarks

The large result query shows modest latency improvement:

![image](https://github.com/user-attachments/assets/65d300ed-ad44-466a-bce2-950b305b02b3)

A query with a response of the same size as above, but with deep nesting
to trigger quadratic behavior shows significant latency improvement
(~12ms to ~2ms for `process_response` span)

![image](https://github.com/user-attachments/assets/355f8e96-a363-4523-a9df-850aba8edb8a)

Small responses (common, historically) don't show any improvement, as
they don't exhibit the issue.

V3_GIT_ORIGIN_REV_ID: f709e4f8a370b46c53f533eef2fef7e772b5cb72