tamer: asg: Move {expr,ident} into object/

Starting to re-organize things to match my mental model of the new system;
the ASG abstraction has changed quite a bit since the early days.

This isn't quite enough, though; see next commit.

DEV-13597

tamer/src/asg/mod.rs

@@ -64,21 +64,21 @@
 //!     if either identifier has not yet been declared.
 
 mod error;
-mod expr;
 mod graph;
-mod ident;
 mod object;
 
 pub mod air;
 
 pub use error::AsgError;
-pub use expr::{Expr, ExprDim, ExprOp};
 pub use graph::{Asg, AsgResult, IndexType};
-pub use ident::{
+pub use object::{
-    FragmentText, Ident, IdentKind, Source, TransitionError, TransitionResult,
+    expr::{Expr, ExprDim, ExprOp},
-    UnresolvedError,
+    ident::{
+        FragmentText, Ident, IdentKind, Source, TransitionError,
+        TransitionResult, UnresolvedError,
+    },
+    Object, ObjectIndex, ObjectKind,
 };
-pub use object::{Object, ObjectIndex, ObjectKind};
 
 /// Default concrete ASG implementation.
 pub type DefaultAsg = graph::Asg;

tamer/src/asg/object.rs

@@ -71,6 +71,9 @@ use crate::{
 use petgraph::graph::NodeIndex;
 use std::{convert::Infallible, fmt::Display, marker::PhantomData};
 
+pub mod expr;
+pub mod ident;
+
 /// An object on the ASG.
 ///
 /// See the [module-level documentation](super) for more information.

tamer/src/asg/object/ident.rs

@@ -19,7 +19,10 @@
 
 //! Identifiers (a type of [object][super::object]).
 
-use super::{object::ObjectRelTo, Asg, AsgError, ObjectIndex, ObjectKind};
+use super::{
+    super::{Asg, AsgError, ObjectIndex, ObjectKind},
+    ObjectRelTo,
+};
 use crate::{
     diagnose::{Annotate, Diagnostic},
     f::Functor,