vim-patch:8.2.2523: Svelte filetype not recognized (#13961)

Problem:    Svelte filetype not recognized.
Solution:   Add a detection rule. (Brian Ryall, closes vim/vim#7858)
c0fcb6e0b1

src/nvim/testdir/test_filetype.vim

@@ -428,6 +428,7 @@ let s:filename_checks = {
     \ 'slrnrc': ['.slrnrc'],
     \ 'slrnsc': ['file.score'],
     \ 'sm': ['sendmail.cf'],
+    \ 'svelte': ['file.svelte'],
     \ 'smarty': ['file.tpl'],
     \ 'smcl': ['file.hlp', 'file.ihlp', 'file.smcl'],
     \ 'smith': ['file.smt', 'file.smith'],