add rego support (#4199)

* add opa fmt fixer for rego files

* add opa linter

* add basic tests for linter and fixer

* add cspell to the docs

autoload/ale/fix/registry.vim

@@ -526,6 +526,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['pascal'],
 \       'description': 'Fix Pascal files with ptop.',
 \   },
+\   'opafmt': {
+\       'function': 'ale#fixers#opafmt#Fix',
+\       'suggested_filetypes': ['rego'],
+\       'description': 'Fix rego files with opa fmt.',
+\   },
 \   'vfmt': {
 \       'function': 'ale#fixers#vfmt#Fix',
 \       'suggested_filetypes': ['v'],

autoload/ale/fixers/opafmt.vim

@@ -0,0 +1,15 @@
+" Description: Fixer for rego files
+
+call ale#Set('opa_fmt_executable', 'opa')
+call ale#Set('opa_fmt_options', '')
+
+function! ale#fixers#opafmt#Fix(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'opa_fmt_executable')
+    let l:options = ale#Var(a:buffer, 'opa_fmt_options')
+
+    return {
+    \   'command': ale#Escape(l:executable)
+    \       . ' fmt'
+    \       . (empty(l:options) ? '' : ' ' . l:options)
+    \}
+endfunction