rename tree_sitter_library in LanguageConfig to 'grammar'

This is not strictly speaking necessary. tree_sitter_library was used by
just one grammar: llvm-mir-yaml, which uses the yaml grammar. This will
make the language more consistent, though. Each language can explicitly
say that they use Some(grammar), defaulting when None to the grammar that
has a grammar_id matching the language's language_id.

helix-core/src/indent.rs

@@ -433,7 +433,7 @@ where
                 comment_token: None,
                 auto_format: false,
                 diagnostic_severity: Severity::Warning,
-                tree_sitter_library: None,
+                grammar: None,
                 language_server: None,
                 indent: Some(IndentationConfiguration {
                     tab_width: 4,

helix-core/src/syntax.rs

@@ -108,7 +108,7 @@ pub struct LanguageConfiguration {
     #[serde(default)]
     pub diagnostic_severity: Severity,
 
-    pub tree_sitter_library: Option<String>, // tree-sitter library name, defaults to language_id
+    pub grammar: Option<String>, // tree-sitter grammar name, defaults to language_id
 
     // content_regex
     #[serde(default, skip_serializing, deserialize_with = "deserialize_regex")]
@@ -444,9 +444,7 @@ impl LanguageConfiguration {
         } else {
             let language = get_language(
                 &crate::RUNTIME_DIR,
-                self.tree_sitter_library
+                self.grammar.as_deref().unwrap_or(&self.language_id),
-                    .as_deref()
-                    .unwrap_or(&self.language_id),
             )
             .map_err(|e| log::info!("{}", e))
             .ok()?;