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

doc/ale-rego.txt

@@ -0,0 +1,50 @@
+===============================================================================
+ALE Rego Integration                                         *ale-rego-options*
+
+
+===============================================================================
+cspell                                                        *ale-rego-cspell*
+
+See |ale-cspell-options|
+
+
+===============================================================================
+opacheck                                                   *ale-rego-opa-check*
+
+g:ale_rego_opacheck_executable                     *g:rego_opacheck_executable*
+                                                   *b:rego_opacheck_executable*
+
+  Type: |String|
+  Default: `'opa'`
+
+  This variable can be changed to use a different executable for opa.
+
+
+g:rego_opacheck_options                               *g:rego_opacheck_options*
+                                                      *b:rego_opacheck_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be changed to pass custom CLI flags to opa check.
+
+
+===============================================================================
+opafmt                                                 *ale-rego-opa-fmt-fixer*
+
+g:ale_opa_fmt_executable                             *g:ale_opa_fmt_executable*
+                                                     *b:ale_opa_fmt_executable*
+
+  Type: |String|
+  Default: `'opa'`
+
+  This variable can be changed to use a different executable for opa.
+
+
+g:ale_opa_fmt_options                                   *g:ale_opa_fmt_options*
+                                                        *b:ale_opa_fmt_options*
+  Type: |String|
+  Default: `''`
+
+
+===============================================================================
+  vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:

doc/ale-supported-languages-and-tools.txt

@@ -489,6 +489,10 @@ Notes:
   * `ols`
   * `reason-language-server`
   * `refmt`
+* Rego
+  * `cspell`
+  * `opacheck`
+  * `opafmt`
 * reStructuredText
   * `alex`
   * `cspell`

doc/ale.txt

@@ -3128,6 +3128,10 @@ documented in additional help files.
     ols...................................|ale-reasonml-ols|
     reason-language-server................|ale-reasonml-language-server|
     refmt.................................|ale-reasonml-refmt|
+  rego....................................|ale-rego-options|
+    cspell................................|ale-rego-cspell|
+    opacheck..............................|ale-rego-opa-check|
+    opafmt................................|ale-rego-opa-fmt-fixer|
   restructuredtext........................|ale-restructuredtext-options|
     cspell................................|ale-restructuredtext-cspell|
     textlint..............................|ale-restructuredtext-textlint|