Divorce JSON and KCL (#4436)

Removes JSON from the KCL object model. Closes https://github.com/KittyCAD/modeling-app/issues/1130 -- it was filed on Nov 27 last year. Hopefully I close it before its one year anniversary.

Changes:

- Removed the UserVal variant from `enum KclValue`. That variant held JSON data.
- Replaced it with several new variants like Number, String, Array (of KCL values), Object (where keys are String and values are KCL values)
- Added a dedicated Sketch variant to KclValue. We used to have a variant like this, but I removed it as an experimental approach to fix this issue. Eventually I decided to undo it and use the approach of this PR instead.
- Removed the `impl_from_arg_via_json` macro, which implemented conversion from KclValue to Rust types by matching the KclValue to its UserVal variant, grabbing the JSON, then deserializing that into the desired Rust type. 
- Instead, replaced it with manual conversion from KclValue to Rust types, using some convenience macros like `field!`

docs/kcl/types/KclNone.md

@@ -0,0 +1,16 @@
+---
+title: "KclNone"
+excerpt: "KCL value for an optional parameter which was not given an argument. (remember, parameters are in the function declaration, arguments are in the function call/application)."
+layout: manual
+---
+
+KCL value for an optional parameter which was not given an argument. (remember, parameters are in the function declaration, arguments are in the function call/application).
+
+**Type:** `object`
+
+
+
+
+
+
+

docs/kcl/types/KclValue.md

@@ -23,8 +23,110 @@ Any KCL value.
 
 | Property | Type | Description | Required |
 |----------|------|-------------|----------|
-| `type` |enum: `UserVal`|  | No |
-| `value` |``|  | No |
+| `type` |enum: `Uuid`|  | No |
+| `value` |`string`|  | No |
+| `__meta` |`[` [`Metadata`](/docs/kcl/types/Metadata) `]`|  | No |
+
+
+----
+
+**Type:** `object`
+
+
+
+
+
+## Properties
+
+| Property | Type | Description | Required |
+|----------|------|-------------|----------|
+| `type` |enum: `Bool`|  | No |
+| `value` |`boolean`|  | No |
+| `__meta` |`[` [`Metadata`](/docs/kcl/types/Metadata) `]`|  | No |
+
+
+----
+
+**Type:** `object`
+
+
+
+
+
+## Properties
+
+| Property | Type | Description | Required |
+|----------|------|-------------|----------|
+| `type` |enum: `Number`|  | No |
+| `value` |`number`|  | No |
+| `__meta` |`[` [`Metadata`](/docs/kcl/types/Metadata) `]`|  | No |
+
+
+----
+
+**Type:** `object`
+
+
+
+
+
+## Properties
+
+| Property | Type | Description | Required |
+|----------|------|-------------|----------|
+| `type` |enum: `Int`|  | No |
+| `value` |`integer`|  | No |
+| `__meta` |`[` [`Metadata`](/docs/kcl/types/Metadata) `]`|  | No |
+
+
+----
+
+**Type:** `object`
+
+
+
+
+
+## Properties
+
+| Property | Type | Description | Required |
+|----------|------|-------------|----------|
+| `type` |enum: `String`|  | No |
+| `value` |`string`|  | No |
+| `__meta` |`[` [`Metadata`](/docs/kcl/types/Metadata) `]`|  | No |
+
+
+----
+
+**Type:** `object`
+
+
+
+
+
+## Properties
+
+| Property | Type | Description | Required |
+|----------|------|-------------|----------|
+| `type` |enum: `Array`|  | No |
+| `value` |`[` [`KclValue`](/docs/kcl/types/KclValue) `]`|  | No |
+| `__meta` |`[` [`Metadata`](/docs/kcl/types/Metadata) `]`|  | No |
+
+
+----
+
+**Type:** `object`
+
+
+
+
+
+## Properties
+
+| Property | Type | Description | Required |
+|----------|------|-------------|----------|
+| `type` |enum: `Object`|  | No |
+| `value` |`object`|  | No |
 | `__meta` |`[` [`Metadata`](/docs/kcl/types/Metadata) `]`|  | No |
 
 
@@ -111,6 +213,38 @@ A face.
 | `__meta` |`[` [`Metadata`](/docs/kcl/types/Metadata) `]`|  | No |
 
 
+----
+
+**Type:** `object`
+
+
+
+
+
+## Properties
+
+| Property | Type | Description | Required |
+|----------|------|-------------|----------|
+| `type` |enum: [`Sketch`](/docs/kcl/types/Sketch)|  | No |
+| `value` |[`Sketch`](/docs/kcl/types/Sketch)| Any KCL value. | No |
+
+
+----
+
+**Type:** `object`
+
+
+
+
+
+## Properties
+
+| Property | Type | Description | Required |
+|----------|------|-------------|----------|
+| `type` |enum: `Sketches`|  | No |
+| `value` |`[` [`Sketch`](/docs/kcl/types/Sketch) `]`|  | No |
+
+
 ----
 An solid is a collection of extrude surfaces.
 
@@ -190,6 +324,23 @@ Data for an imported geometry.
 
 ----
 
+**Type:** `object`
+
+
+
+
+
+## Properties
+
+| Property | Type | Description | Required |
+|----------|------|-------------|----------|
+| `type` |enum: [`KclNone`](/docs/kcl/types/KclNone)|  | No |
+| `value` |[`KclNone`](/docs/kcl/types/KclNone)| Any KCL value. | No |
+| `__meta` |`[` [`Metadata`](/docs/kcl/types/Metadata) `]`|  | No |
+
+
+----
+