[FIRRTL] DontTouchAnnotation as Symbol and Deduplication

Nobody has claimed this yet.

The modeling of `DontTouchAnnotation` as a symbol destroys some information that may be necessary for an SFC-exact implementation of deduplication.

Consider the following circuit. Modules `A` and `A_` are structurally equivalent and should deduplicate. `A` has a `DontTouchAnnotation` on a wire inside it. This is not supposed to block deduplication.

```scala
circuit Top : %[[
{
"class":"firrtl.transforms.DontTouchAnnotation",
"target":"Top.A.b"
}
]]
module Top :
inst a1 of A
inst a2 of A_
module A :
output x: UInt<1>
wire b: UInt<1>
b is invalid
x <= b
module A_ :
output x: UInt<1>
wire b: UInt<1>
b is invalid
x <= b
```

When we parse this in, this specific annotations becomes a symbol `@b`:

```mlir
module {
firrtl.circuit "Top" {
firrtl.module @Top() {
%a1_x = firrtl.instance a1 @A(out x: !firrtl.uint<1>)
%a2_x = firrtl.instance a2 @A_(out x: !firrtl.uint<1>)
}
firrtl.module @A(out %x: !firrtl.uint<1>) {
%b = firrtl.wire sym @b : !firrtl.uint<1>
%invalid_ui1 = firrtl.invalidvalue : !firrtl.uint<1>
firrtl.connect %b, %invalid_ui1 : !firrtl.uint<1>, !firrtl.uint<1>
firrtl.connect %x, %b : !firrtl.uint<1>, !firrtl.uint<1>
}
firrtl.module @A_(out %x: !firrtl.uint<1>) {
%b = firrtl.wire : !firrtl.uint<1>
%invalid_ui1 = firrtl.invalidvalue : !firrtl.uint<1>
firrtl.connect %b, %invalid_ui1 : !firrtl.uint<1>, !firrtl.uint<1>
firrtl.connect %x, %b : !firrtl.uint<1>, !firrtl.uint<1>
}
}
}
```

After deduplication, the circuit looks like with `@b` applied to the deduplicated wire. The effect of the annotation now applies to both wires:
```mlir
module {
firrtl.circuit "Top" {
firrtl.module @Top() {
%a1_x = firrtl.instance a1 @A(out x: !firrtl.uint<1>)
%a2_x = firrtl.instance a2 @A(out x: !firrtl.uint<1>)
}
firrtl.module @A(out %x: !firrtl.uint<1>) {
%invalid_ui1 = firrtl.invalidvalue : !firrtl.uint<1>
%b = firrtl.wire sym @b : !firrtl.uint<1>
firrtl.connect %b, %invalid_ui1 {annotations = []} : !firrtl.uint<1>, !firrtl.uint<1>
firrtl.connect %x, %b {annotations = []} : !firrtl.uint<1>, !firrtl.uint<1>
}
}
}
```

In contrast, the SFC produces a non-local annotation targeting the original instance's wire:
```scala
circuit Top :
module A :
output x : UInt<1>

wire b : UInt<1> @[dont-touch.scala 33:15]
b is invalid @[dont-touch.scala 34:5]
x <= b @[dont-touch.scala 36:5]

module Top :

inst a1 of A @[dont-touch.scala 47:18]
inst a2 of A @[dont-touch.scala 48:18]
```
```json
[
{
"class":"firrtl.transforms.DontTouchAnnotation",
"target":"~Top|Top/a1:A>b"
}
]
```

I don't have an opinion or evidence that this is problematic, yet. This is just reporting an SFC deviation.

No source file or test is named, and the report does not specify a desired change. Start by tracing FIRRTL DontTouchAnnotation handling through deduplication and comparing the result with the SFC output shown. Done requires establishing whether symbolizing @b changes annotation scope and defining the expected behavior.

Written by the indexing model from the issue text.