Add support for the Musi language (mui)

Autonym according to Ethnologue is "Baso Palembang".
This is also the name most commonly used by the
language's speakers according to the article
Alsamadani, Mardheya; Taibah, Samar (2019).
"Types and Functions of Reduplication in Palembang".
Journal of the Southeast Asian Linguistics Society.

Bug: T364291
Change-Id: I4a867a8671ab32366aa459d49361682305b67dcb

RELEASE-NOTES-1.43

@@ -117,6 +117,7 @@ Below only new and removed languages are listed, as well as changes to languages
 because of Phabricator reports.
 
 * (T290657) Added language support for Levantine Arabic (apc).
+* (T364291) Added language support for Musi, also known as Palembang (mui).
 * …
 
 === Breaking changes in 1.43 ===

includes/languages/data/Names.php

@@ -351,6 +351,7 @@ class Names {
 		'ms' => 'Bahasa Melayu', # Malay
 		'ms-arab' => 'بهاس ملايو', # Malay (Arabic Jawi script)
 		'mt' => 'Malti', # Maltese
+		'mui' => 'Baso Palembang', # Musi/Palembang
 		'mus' => 'Mvskoke', # Muskogee/Creek
 		'mwl' => 'Mirandés', # Mirandese
 		'my' => 'မြန်မာဘာသာ', # Burmese

languages/messages/MessagesMui.php

@@ -0,0 +1,10 @@
+<?php
+/** Musi (Baso Palembang)
+ *
+ * @file
+ * @ingroup Language
+ */
+
+$fallback = 'id';
+
+$linkTrail = '/^([a-zéÉ]+)(.*)$/sDu';