Add jq_raw function to simplexpr

[RomanHargrave]

Description

This is a fairly simple change which adds a jq_raw function - jq_raw() shares jq()'s implementation, with the difference being that top level strings are not quoted (nested strings are quoted). This behavior is consistent with jq's documented and observed behavior for --raw-output.

This PR resolves #745.

For instance, we see the following behavior with orthodox jq

$ echo '{"a": ["b"]}' | jq -r '.a'
[
  "b"
]
$ echo '{"a": ["b"]}' | jq -r '.a[]'
b

Similarly, the expressions

{jq_raw("{\"a\": [\"b\"]}", ".a")}
{jq_raw("{\"a\": [\"b\"]}", ".a[]")}

Produce the following output,

Usage

Use jq_raw as you would jq when unquoted strings are needed (typically for display)

Checklist

Please make sure you can check all the boxes that apply to this PR.

• All widgets I've added are correctly documented.
• I added my changes to CHANGELOG.md, if appropriate.
• The documentation in the docs/src directory has been adjusted to reflect my changes.
• I used cargo fmt to automatically format all code before committing