ls: honor LC_TIME for --time-style=locale via uucore helper

Add format_system_time_locale_aware in uucore::time that runs the
format string through i18n::datetime::localize_format_string when a
non-C LC_TIME locale is active, and route ls's display_date through
it. Fixes month names and alternate-calendar years (Persian,
Buddhist, Ethiopian) matching GNU. Also generalize uutests'
is_locale_available to derive the expected charmap from the locale
suffix so non-UTF-8 locales work, and consolidate the ls locale
tests into a single data-driven case.

Author: sylvestre

src/uu/ls/src/display.rs

@@ -56,7 +56,7 @@ use uucore::{
     os_str_as_bytes_lossy,
     quoting_style::{QuotingStyle, locale_aware_escape_dir_name, locale_aware_escape_name},
     show,
-    time::{FormatSystemTimeFallback, format_system_time_locale_aware},
+    time::{FormatSystemTimeFallback, NamePadding, format_system_time_locale_aware},
 };
 
 use crate::colors::{StyleManager, color_name};
@@ -620,7 +620,13 @@ fn display_date(
         _ => &config.time_format_recent,
     };
 
-    format_system_time_locale_aware(out, time, fmt, FormatSystemTimeFallback::Integer)
+    format_system_time_locale_aware(
+        out,
+        time,
+        fmt,
+        FormatSystemTimeFallback::Integer,
+        NamePadding::Padded,
+    )
 }
 
 fn display_len_or_rdev(metadata: &Metadata, config: &Config) -> SizeOrDeviceId {

src/uucore/src/lib/features/time.rs

@@ -16,6 +16,21 @@ use std::time::{SystemTime, UNIX_EPOCH};
 use crate::error::{UResult, USimpleError};
 use crate::show_error;
 
+#[cfg(feature = "i18n-datetime")]
+pub use crate::i18n::datetime::NamePadding;
+
+/// Controls whether locale name lookups return raw or padded names.
+///
+/// Without the `i18n-datetime` feature the parameter is accepted but ignored.
+#[cfg(not(feature = "i18n-datetime"))]
+#[derive(Clone, Copy)]
+pub enum NamePadding {
+    /// Raw names with no trailing padding — for `date` and similar utilities.
+    Raw,
+    /// Names padded to uniform display width — for columnar output like `ls`.
+    Padded,
+}
+
 /// Format the given date according to this time format style.
 fn format_zoned<W: Write>(out: &mut W, zoned: Zoned, fmt: &str) -> UResult<()> {
     let tm = BrokenDownTime::from(&zoned);
@@ -108,6 +123,7 @@ pub fn format_system_time_locale_aware<W: Write>(
     time: SystemTime,
     fmt: &str,
     mode: FormatSystemTimeFallback,
+    padding: NamePadding,
 ) -> UResult<()> {
     #[cfg(feature = "i18n-datetime")]
     {