Feature: Filter by invert_filter: reverse match

Mimic grep's -v option.

Allows dust to only match files that do not match the given filter

src/dir_walker.rs

@@ -1,6 +1,7 @@
 use std::fs;
 
 use crate::node::Node;
+use crate::utils::is_filtered_out_due_to_invert_regex;
 use crate::utils::is_filtered_out_due_to_regex;
 use rayon::iter::ParallelBridge;
 use rayon::prelude::ParallelIterator;
@@ -20,6 +21,7 @@ use crate::platform::get_metadata;
 pub struct WalkData {
     pub ignore_directories: HashSet<PathBuf>,
     pub filter_regex: Option<Regex>,
+    pub invert_filter_regex: Option<Regex>,
     pub allowed_filesystems: HashSet<u64>,
     pub use_apparent_size: bool,
     pub by_filecount: bool,
@@ -96,6 +98,13 @@ fn ignore_file(entry: &DirEntry, walk_data: &WalkData) -> bool {
         return true;
     }
 
+    if walk_data.invert_filter_regex.is_some()
+        && entry.path().is_file()
+        && is_filtered_out_due_to_invert_regex(&walk_data.invert_filter_regex, &entry.path())
+    {
+        return true;
+    }
+
     (is_dot_file && walk_data.ignore_hidden) || is_ignored_path
 }
 
@@ -123,6 +132,7 @@ fn walk(dir: PathBuf, permissions_flag: &AtomicBool, walk_data: &WalkData) -> Op
                                 entry.path(),
                                 vec![],
                                 &walk_data.filter_regex,
+                                &walk_data.invert_filter_regex,
                                 walk_data.use_apparent_size,
                                 data.is_symlink(),
                                 data.is_file(),
@@ -143,6 +153,7 @@ fn walk(dir: PathBuf, permissions_flag: &AtomicBool, walk_data: &WalkData) -> Op
         dir,
         children,
         &walk_data.filter_regex,
+        &walk_data.invert_filter_regex,
         walk_data.use_apparent_size,
         false,
         false,