[ty] Remap Jupyter notebook cell indices in ruff_db (#19698)

## Summary

This PR remaps ranges in Jupyter notebooks from simple `row:column`
indices in the concatenated source code to `cell:row:col` to match
Ruff's output. This is probably not a likely change to land upstream in
`annotate-snippets`, but I didn't see a good way around it.

The remapping logic is taken nearly verbatim from here:


cd6bf1457d/crates/ruff_linter/src/message/text.rs (L212-L222)


## Test Plan

New `full` rendering test for a notebook

I was mainly focused on Ruff, but in local tests this also works for ty:

```
error[invalid-assignment]: Object of type `Literal[1]` is not assignable to `str`
 --> Untitled.ipynb:cell 1:3:1
  |
1 | import math
2 |
3 | x: str = 1
  | ^
  |
info: rule `invalid-assignment` is enabled by default

error[invalid-assignment]: Object of type `Literal[1]` is not assignable to `str`
 --> Untitled.ipynb:cell 2:3:1
  |
1 | import math
2 |
3 | x: str = 1
  | ^
  |
info: rule `invalid-assignment` is enabled by default
```

This isn't a duplicate diagnostic, just an unimaginative example:

```py
# cell 1
import math

x: str = 1
# cell 2
import math

x: str = 1
```

crates/ruff_annotate_snippets/src/snippet.rs

@@ -75,6 +75,10 @@ pub struct Snippet<'a> {
     pub(crate) annotations: Vec<Annotation<'a>>,
 
     pub(crate) fold: bool,
+
+    /// The optional cell index in a Jupyter notebook, used for reporting source locations along
+    /// with the ranges on `annotations`.
+    pub(crate) cell_index: Option<usize>,
 }
 
 impl<'a> Snippet<'a> {
@@ -85,6 +89,7 @@ impl<'a> Snippet<'a> {
             source,
             annotations: vec![],
             fold: false,
+            cell_index: None,
         }
     }
 
@@ -113,6 +118,12 @@ impl<'a> Snippet<'a> {
         self.fold = fold;
         self
     }
+
+    /// Attach a Jupyter notebook cell index.
+    pub fn cell_index(mut self, index: Option<usize>) -> Self {
+        self.cell_index = index;
+        self
+    }
 }
 
 /// An annotation for a [`Snippet`].