Add word_characters to language overrides & use for more things

Use word_characters to feed completion trigger characters as well and
also recognize kebab as a potential sub-word splitter. This is fine for
non-kebab-case languages because we'd only ever attempt to split a word
with a kebab in it in language scopes which are kebab-cased

Co-Authored-By: Max Brunsfeld <max@zed.dev>

crates/language/src/language.rs

@@ -370,6 +370,8 @@ pub struct LanguageConfigOverride {
     pub block_comment: Override<(Arc<str>, Arc<str>)>,
     #[serde(skip_deserializing)]
     pub disabled_bracket_ixs: Vec<u16>,
+    #[serde(default)]
+    pub word_characters: Override<HashSet<char>>,
 }
 
 #[derive(Clone, Deserialize, Debug)]
@@ -1557,6 +1559,13 @@ impl LanguageScope {
         .map(|e| (&e.0, &e.1))
     }
 
+    pub fn word_characters(&self) -> Option<&HashSet<char>> {
+        Override::as_option(
+            self.config_override().map(|o| &o.word_characters),
+            Some(&self.language.config.word_characters),
+        )
+    }
+
     pub fn brackets(&self) -> impl Iterator<Item = (&BracketPair, bool)> {
         let mut disabled_ids = self
             .config_override()