indent: use_list indentation, fix indentation bug on open_below

use std::{
  time::Duration // <- pressing `o` here would use }'s indent instead of prev line
}

helix-core/src/indent.rs

@@ -78,6 +78,8 @@ fn calculate_indentation(node: Option<Node>, newline: bool) -> usize {
         "field_expression",
         //
         "where_clause",
+        //
+        "use_list",
     ];
 
     let outdent = &["where", "}", "]", ")"];
@@ -213,6 +215,12 @@ mod test {
     fn test_suggested_indent_for_line() {
         let doc = Rope::from(
             "
+use std::{
+    io::{self, stdout, Stdout, Write},
+    path::PathBuf,
+    sync::Arc,
+    time::Duration,
+}
 mod test {
     fn hello_world() {
         1 + 1;

helix-term/src/commands.rs

@@ -644,7 +644,7 @@ pub fn open_below(cx: &mut Context) {
         let indent_level = helix_core::indent::suggested_indent_for_pos(
             doc.syntax.as_ref(),
             &doc.state,
-            index,
+            index - 1, // need to match the indentation to the prev line
             true,
         );
         let indent = " ".repeat(TAB_WIDTH).repeat(indent_level);