refactor: consolidate to_hex helper function (DRY)

Move the to_hex helper function to module level so it can be used by
both DistroboxCommandRunnerResponse and the test utilities. This
removes code duplication and keeps the hex encoding logic in one place.

Author: ranfdev

src/backends/distrobox/distrobox.rs

@@ -20,6 +20,11 @@ use crate::backends::desktop_file::*;
 const POSIX_FIND_AND_CONCAT_DESKTOP_FILES: &str =
     include_str!("POSIX_FIND_AND_CONCAT_DESKTOP_FILES.sh");
 
+/// Encode a string as hex (matching the shell script's base16 function)
+fn to_hex(s: &str) -> String {
+    s.bytes().map(|b| format!("{:02x}", b)).collect()
+}
+
 #[derive(Deserialize, Debug)]
 struct DesktopFiles {
     #[serde(deserialize_with = "DesktopFiles::deserialize_path")]
@@ -333,11 +338,6 @@ pub enum DistroboxCommandRunnerResponse {
 }
 
 impl DistroboxCommandRunnerResponse {
-    /// Helper to encode a string as hex (matching the shell script's base16 function)
-    fn to_hex(s: &str) -> String {
-        s.bytes().map(|b| format!("{:02x}", b)).collect()
-    }
-
     pub fn common_distros() -> LazyCell<Vec<ContainerInfo>> {
         LazyCell::new(|| {
             [
@@ -474,7 +474,7 @@ impl DistroboxCommandRunnerResponse {
         ));
 
         // Build desktop files TOML with hex encoding (matching POSIX_FIND_AND_CONCAT_DESKTOP_FILES.sh output)
-        let mut toml = format!("home_dir=\"{}\"\n", Self::to_hex("/home/me"));
+        let mut toml = format!("home_dir=\"{}\"\n", to_hex("/home/me"));
 
         toml.push_str("[system]\n");
         for (filename, name, icon) in apps {
@@ -490,8 +490,8 @@ impl DistroboxCommandRunnerResponse {
             );
             toml.push_str(&format!(
                 "\"{}\"=\"{}\"\n",
-                Self::to_hex(&path),
-                Self::to_hex(&content)
+                to_hex(&path),
+                to_hex(&content)
             ));
         }
 
@@ -1072,11 +1072,6 @@ mod tests {
     use super::*;
     use smol::block_on;
 
-    /// Helper to encode a string as hex (matching the shell script's base16 function)
-    fn to_hex(s: &str) -> String {
-        s.bytes().map(|b| format!("{:02x}", b)).collect()
-    }
-
     /// Helper to generate TOML output matching the shell script format
     fn make_desktop_files_toml(
         home_dir: &str,