patch 9.1.1268: filetype: dax files are not recognized

Problem:  filetype: dax files are not recognized
Solution: detect "*.dax" as dax filetype, include dax filetype and
          syntax plugin (Anarion Dunedain)

Data Analysis Expressions (DAX) is a formula expression language used in
Analysis Services, Power BI, and Power Pivot in Excel. DAX formulas
include functions, operators, and values to perform advanced
calculations and queries on data in related tables and columns in
tabular data models.

DAX language overview:
- https://learn.microsoft.com/en-us/dax/dax-overview

closes: #17035

Signed-off-by: Anarion Dunedain <anarion80@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index 531c500..6a9b2b0 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -213,6 +213,7 @@
     dafny: ['file.dfy'],
     dart: ['file.dart', 'file.drt'],
     datascript: ['file.ds'],
+    dax: ['file.dax'],
     dcd: ['file.dcd'],
     deb822sources: ['/etc/apt/sources.list.d/file.sources', 'any/etc/apt/sources.list.d/file.sources'],
     debchangelog: ['changelog.Debian', 'changelog.dch', 'NEWS.Debian', 'NEWS.dch', '/debian/changelog'],
diff --git a/src/version.c b/src/version.c
index 47104ef..192fd0f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1268,
+/**/
     1267,
 /**/
     1266,