Move type inlay hint truncation to language server

This commit implements a general truncation framework for HirFormatter
that keeps track of how much has been output so far. This information
can then be used to perform truncation inside the language server,
instead of relying on the client.

Initial support is implemented for truncating types hints using the
maxInlayHintLength server config option. The existing solution in the
VSCode extension has been removed in favor of letting the server
truncate type hints.

crates/ra_lsp_server/src/config.rs

@@ -29,6 +29,8 @@ pub struct ServerConfig {
 
     pub lru_capacity: Option<usize>,
 
+    pub max_inlay_hint_length: Option<usize>,
+
     /// For internal usage to make integrated tests faster.
     #[serde(deserialize_with = "nullable_bool_true")]
     pub with_sysroot: bool,
@@ -44,6 +46,7 @@ impl Default for ServerConfig {
             exclude_globs: Vec::new(),
             use_client_watching: false,
             lru_capacity: None,
+            max_inlay_hint_length: None,
             with_sysroot: true,
             feature_flags: FxHashMap::default(),
         }

crates/ra_lsp_server/src/main_loop.rs

@@ -123,6 +123,7 @@ pub fn main_loop(
                     .and_then(|it| it.folding_range.as_ref())
                     .and_then(|it| it.line_folding_only)
                     .unwrap_or(false),
+                max_inlay_hint_length: config.max_inlay_hint_length,
             }
         };
 

crates/ra_lsp_server/src/main_loop/handlers.rs

@@ -870,7 +870,7 @@ pub fn handle_inlay_hints(
     let analysis = world.analysis();
     let line_index = analysis.file_line_index(file_id)?;
     Ok(analysis
-        .inlay_hints(file_id)?
+        .inlay_hints(file_id, world.options.max_inlay_hint_length)?
         .into_iter()
         .map(|api_type| InlayHint {
             label: api_type.label.to_string(),

crates/ra_lsp_server/src/world.rs

@@ -28,6 +28,7 @@ pub struct Options {
     pub publish_decorations: bool,
     pub supports_location_link: bool,
     pub line_folding_only: bool,
+    pub max_inlay_hint_length: Option<usize>,
 }
 
 /// `WorldState` is the primary mutable state of the language server