refactor: Remove bookkeeping abstraction from turbo config (#6809)

### Description

I removed the bookkeeping abstraction that we ported from Go. It wasn't
necessary since we can use `Option` to detect if a field is explicitly
set versus not. Also renamed `RawTurboJSON` to be `RawTurboJson` to fit
with the other names.

### Testing Instructions

The existing tests should suffice.


Closes TURBO-1945

crates/turborepo-lib/src/commands/link.rs

@@ -593,7 +593,7 @@ mod test {
     use crate::{
         cli::LinkTarget,
         commands::{link, CommandBase},
-        config::{RawTurboJSON, TurborepoConfigBuilder},
+        config::{RawTurboJson, TurborepoConfigBuilder},
         Args,
     };
 
@@ -728,7 +728,7 @@ mod test {
 
         // verify space id is added to turbo.json
         let turbo_json_contents = fs::read_to_string(&turbo_json_file).unwrap();
-        let turbo_json: RawTurboJSON = serde_json::from_str(&turbo_json_contents).unwrap();
+        let turbo_json: RawTurboJson = serde_json::from_str(&turbo_json_contents).unwrap();
         assert_eq!(
             turbo_json.experimental_spaces.unwrap().id.unwrap(),
             turborepo_vercel_api_mock::EXPECTED_SPACE_ID

crates/turborepo-lib/src/commands/prune.rs

@@ -14,7 +14,7 @@ use turborepo_repository::{
 use turborepo_ui::BOLD;
 
 use super::CommandBase;
-use crate::config::RawTurboJSON;
+use crate::config::RawTurboJson;
 
 #[derive(Debug, thiserror::Error)]
 pub enum Error {
@@ -426,7 +426,7 @@ impl<'a> Prune<'a> {
             }
             Err(e) => return Err(e.into()),
         };
-        let turbo_json: RawTurboJSON = serde_json::from_reader(json_comments::StripComments::new(
+        let turbo_json: RawTurboJson = serde_json::from_reader(json_comments::StripComments::new(
             turbo_json_contents.as_slice(),
         ))?;
 

crates/turborepo-lib/src/config/mod.rs

@@ -4,7 +4,9 @@ mod turbo_config;
 use std::io;
 
 use thiserror::Error;
-pub use turbo::{validate_extends, validate_no_package_task_syntax, RawTurboJSON, TurboJson};
+pub use turbo::{
+    validate_extends, validate_no_package_task_syntax, RawTaskDefinition, RawTurboJson, TurboJson,
+};
 pub use turbo_config::{ConfigurationOptions, TurborepoConfigBuilder};
 use turbopath::AbsoluteSystemPathBuf;