Use AnyValue: {} for the any type in OpenAPI (#1773)

Recursive type aliases [are
broken](https://discord.com/channels/1119368998161752075/1359498024790917231)
in OpenAPI. Use the [Any
Type](https://swagger.io/docs/specification/v3_0/data-models/data-types/#any-type)
to fix them.
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----

> [!IMPORTANT]
> Replaces `anyOf` with `AnyValue` in OpenAPI to fix recursive type
alias handling, updating both code generation and integration tests.
> 
>   - **Behavior**:
> - Replaces `anyOf: []` with `AnyValue: {}` in `openapi.rs` and
`openapi.yaml` to handle recursive type aliases in OpenAPI.
> - Updates `TypeSpec::AnyValue` in `openapi.rs` to use `HashMap` for
`any_value`.
>   - **Code Changes**:
> - Modifies `ToTypeReferenceInTypeDefinition` for
`FieldType::RecursiveTypeAlias` in `openapi.rs` to use `AnyValue`.
> - Updates `TypeSpec` enum in `openapi.rs` to include `AnyValue` with
`HashMap`.
>   - **Tests**:
> - Updates `openapi.yaml` in `baml_client` integration tests to reflect
changes from `anyOf` to `AnyValue` for various paths.
> 
> <sup>This description was created by </sup>[<img alt="Ellipsis"
src="https://img.shields.io/badge/Ellipsis-blue?color=175173">](https://www.ellipsis.dev?ref=BoundaryML%2Fbaml&utm_source=github&utm_medium=referral)<sup>
for 8da98aa. It will automatically
update as commits are pushed.</sup>

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Author: antoniosarosi

engine/language_client_codegen/src/openapi.rs

@@ -1,4 +1,4 @@
-use std::path::PathBuf;
+use std::{collections::HashMap, path::PathBuf};
 
 use anyhow::{Context, Result};
 use baml_types::{BamlMediaType, FieldType, LiteralValue, TypeValue};
@@ -558,7 +558,9 @@ impl<'ir> ToTypeReferenceInTypeDefinition<'ir> for FieldType {
                     r#const: None,
                     nullable: false,
                 },
-                type_spec: TypeSpec::AnyValue { any_of: vec![] },
+                type_spec: TypeSpec::AnyValue {
+                    any_value: HashMap::new(),
+                },
             },
             FieldType::Literal(v) => TypeSpecWithMeta {
                 meta: TypeMetadata {
@@ -682,7 +684,9 @@ impl<'ir> ToTypeReferenceInTypeDefinition<'ir> for FieldType {
                 }
                 None => base.to_type_spec(_ir)?,
             },
-            FieldType::Arrow(_) => todo!("Arrow types should not be used in generated type definitions"),
+            FieldType::Arrow(_) => {
+                todo!("Arrow types should not be used in generated type definitions")
+            }
         })
     }
 }
@@ -732,9 +736,11 @@ enum TypeSpec {
         #[serde(rename = "oneOf", alias = "oneOf")]
         one_of: Vec<TypeSpecWithMeta>,
     },
+    // Any Type in OpenAPI version 3.
+    // https://swagger.io/docs/specification/v3_0/data-models/data-types/#any-type
     AnyValue {
-        #[serde(rename = "anyOf", alias = "anyOf")]
-        any_of: Vec<TypeSpecWithMeta>,
+        #[serde(rename = "AnyValue", alias = "AnyValue")]
+        any_value: HashMap<String, TypeSpecWithMeta>,
     },
 }