Add auto-fixer for crystal (#4016)

autoload/ale/fix/registry.vim

@@ -431,6 +431,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['hcl', 'terraform'],
 \       'description': 'Fix tf and hcl files with terraform fmt.',
 \   },
+\   'crystal': {
+\       'function': 'ale#fixers#crystal#Fix',
+\       'suggested_filetypes': ['cr'],
+\       'description': 'Fix cr (crystal).',
+\   },
 \   'ktlint': {
 \       'function': 'ale#fixers#ktlint#Fix',
 \       'suggested_filetypes': ['kt', 'kotlin'],