patch 9.1.1503: filetype: haxe files are not recognized

Problem:  filetype: haxe files are not recognized
Solution: detect *.hx files as haxe filetype (0xadk)

References:
- https://haxe.org/
- https://code.haxe.org/category/beginner/hello-world.html

closes: #17644

Signed-off-by: 0xadk <0xadk@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/filetype.vim

@@ -1100,6 +1100,9 @@ au BufNewFile,BufRead *.persistentmodels	setf haskellpersistent
 au BufNewFile,BufRead *.ht			setf haste
 au BufNewFile,BufRead *.htpp			setf hastepreproc
 
+" Haxe
+au BufNewFile,BufRead *.hx			setf haxe
+
 " HCL
 au BufRead,BufNewFile *.hcl			setf hcl
 

src/testdir/test_filetype.vim

@@ -348,6 +348,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     haskellpersistent: ['file.persistentmodels'],
     haste: ['file.ht'],
     hastepreproc: ['file.htpp'],
+    haxe: ['file.hx'],
     hb: ['file.hb'],
     hcl: ['file.hcl'],
     heex: ['file.heex'],

src/version.c

@@ -719,6 +719,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1503,
 /**/
     1502,
 /**/