Make word completions less intrusive (#36745)

Introduce `min_words_query_len` threshold for automatic word completion
display, and set it to 3 by default.

Re-enable word completions in Markdown and Plaintext.

Release Notes:

- Introduced `min_words_query_len` threshold for automatic word
completion display, and set it to 3 by default to make them less
intrusive

crates/language/src/language_settings.rs

@@ -350,6 +350,12 @@ pub struct CompletionSettings {
     /// Default: `fallback`
     #[serde(default = "default_words_completion_mode")]
     pub words: WordsCompletionMode,
+    /// How many characters has to be in the completions query to automatically show the words-based completions.
+    /// Before that value, it's still possible to trigger the words-based completion manually with the corresponding editor command.
+    ///
+    /// Default: 3
+    #[serde(default = "default_3")]
+    pub words_min_length: usize,
     /// Whether to fetch LSP completions or not.
     ///
     /// Default: true
@@ -359,7 +365,7 @@ pub struct CompletionSettings {
     /// When set to 0, waits indefinitely.
     ///
     /// Default: 0
-    #[serde(default = "default_lsp_fetch_timeout_ms")]
+    #[serde(default)]
     pub lsp_fetch_timeout_ms: u64,
     /// Controls how LSP completions are inserted.
     ///
@@ -405,8 +411,8 @@ fn default_lsp_insert_mode() -> LspInsertMode {
     LspInsertMode::ReplaceSuffix
 }
 
-fn default_lsp_fetch_timeout_ms() -> u64 {
-    0
+fn default_3() -> usize {
+    3
 }
 
 /// The settings for a particular language.
@@ -1468,6 +1474,7 @@ impl settings::Settings for AllLanguageSettings {
             } else {
                 d.completions = Some(CompletionSettings {
                     words: mode,
+                    words_min_length: 3,
                     lsp: true,
                     lsp_fetch_timeout_ms: 0,
                     lsp_insert_mode: LspInsertMode::ReplaceSuffix,