Add Jupyter Notebook document change snapshot test (#11944)

## Summary

Closes #11914.

This PR introduces a snapshot test that replays the LSP requests made
during a document formatting request, and confirms that the notebook
document is updated in the expected way.

crates/ruff_server/src/session/index.rs

@@ -49,7 +49,7 @@ enum DocumentController {
 /// This query can 'select' a text document, full notebook, or a specific notebook cell.
 /// It also includes document settings.
 #[derive(Clone)]
-pub(crate) enum DocumentQuery {
+pub enum DocumentQuery {
     Text {
         file_url: Url,
         document: Arc<TextDocument>,
@@ -519,7 +519,7 @@ impl DocumentQuery {
     }
 
     /// Attempts to access the underlying notebook document that this query is selecting.
-    pub(crate) fn as_notebook(&self) -> Option<&NotebookDocument> {
+    pub fn as_notebook(&self) -> Option<&NotebookDocument> {
         match self {
             Self::Notebook { notebook, .. } => Some(notebook),
             Self::Text { .. } => None,

crates/ruff_server/src/session/index/ruff_settings.rs

@@ -18,7 +18,7 @@ use walkdir::WalkDir;
 
 use crate::session::settings::{ConfigurationPreference, ResolvedEditorSettings};
 
-pub(crate) struct RuffSettings {
+pub struct RuffSettings {
     /// The path to this configuration file, used for debugging.
     /// The default fallback configuration does not have a file path.
     path: Option<PathBuf>,

crates/ruff_server/src/session/settings.rs

@@ -60,7 +60,7 @@ pub(crate) enum ConfigurationPreference {
 #[derive(Debug, Deserialize, Default)]
 #[cfg_attr(test, derive(PartialEq, Eq))]
 #[serde(rename_all = "camelCase")]
-pub(crate) struct ClientSettings {
+pub struct ClientSettings {
     configuration: Option<String>,
     fix_all: Option<bool>,
     organize_imports: Option<bool>,