vim-patch:9.1.2109: filetype: NetLinx fires are not recognized

Problem:  filetype: NetLinx fires are not recognized
Solution: Detect *.axs and *.axi as netlinx filetype
          (kb).

Reference:
- https://www.amx.com/en/site_elements/amx-language-reference-guide-netlinx-programming-language
- https://kielthecoder.com/2021/06/11/netlinx-getting-started/

closes: vim/vim#19249

6963e3b8bf

Co-authored-by: kb <kim@simple.industries>

runtime/lua/vim/filetype.lua

@@ -848,6 +848,8 @@ local extension = {
   NSP = 'natural',
   NSS = 'natural',
   ncf = 'ncf',
+  axs = 'netlinx',
+  axi = 'netlinx',
   nginx = 'nginx',
   ncl = 'nickel',
   nim = 'nim',

test/old/testdir/test_filetype.vim

@@ -575,6 +575,7 @@ func s:GetFilenameChecks() abort
     \ 'ncf': ['file.ncf'],
     \ 'neomuttlog': ['/home/user/.neomuttdebug1'],
     \ 'neomuttrc': ['Neomuttrc', '.neomuttrc', '.neomuttrc-file', '/.neomutt/neomuttrc', '/.neomutt/neomuttrc-file', 'Neomuttrc', 'Neomuttrc-file', 'any/.neomutt/neomuttrc', 'any/.neomutt/neomuttrc-file', 'neomuttrc', 'neomuttrc-file'],
+    \ 'netlinx': ['file.axs', 'file.axi'],
     \ 'netrc': ['.netrc'],
     \ 'nginx': ['file.nginx', 'nginxfile.conf', 'filenginx.conf', 'any/etc/nginx/file', 'any/usr/local/nginx/conf/file', 'any/nginx/file.conf'],
     \ 'nickel': ['file.ncl'],