Add Yara yls support (#4886)

This adds Yara support to ALE using Avast's language server for Yara:
https://avast.github.io/yls/

A ".git" folder is used to determine the project_root so this means the
Yara rules must be in a git repo for the integration to work.

The server only have 1 optional argument (-v, --verbose). Since this is
the case, no additional configuration options are available.

---------

Co-authored-by: w0rp <w0rp@users.noreply.github.com>

ale_linters/yara/yls.vim

@@ -0,0 +1,18 @@
+" Author: TcM1911
+" Description: A language server for Yara.
+
+call ale#Set('yara_yls_executable', 'yls')
+
+function! ale_linters#yara#yls#FindProjectRoot(buffer) abort
+    let l:project_root = ale#path#FindNearestDirectory(a:buffer, '.git')
+
+    return !empty(l:project_root) ? (ale#path#Upwards(l:project_root)[1]) : ''
+endfunction
+
+call ale#linter#Define('yara', {
+\   'name': 'yls',
+\   'lsp': 'stdio',
+\   'executable': {b -> ale#Var(b, 'yara_yls_executable')},
+\   'command': '%e -v',
+\   'project_root': function('ale_linters#yara#yls#FindProjectRoot'),
+\})

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

@@ -737,6 +737,8 @@ Notes:
   * `yq`
 * YANG
   * `yang-lsp`
+* Yara
+  * `yls`
 * Zeek
   * `zeek`!!
 * Zig

doc/ale-yara.txt

@@ -0,0 +1,22 @@
+===============================================================================
+ALE Yara Integration                                         *ale-yara-options*
+                                                         *ale-integration-yara*
+
+===============================================================================
+Integration Information
+
+  Currently, the only supported linter for yara is yls.
+
+
+===============================================================================
+yls                                                              *ale-yara-yls*
+
+g:ale_yara_yls_executable                           *g:ale_yara_yls_executable*
+                                                    *b:ale_yara_yls_executable*
+  Type: |String|
+  Default: `'yls'`
+
+  This variable can be modified to change the executable path for `yls`.
+
+===============================================================================
+  vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:

doc/ale.txt

@@ -3525,6 +3525,8 @@ documented in additional help files.
     yq....................................|ale-yaml-yq|
   yang....................................|ale-yang-options|
     yang-lsp..............................|ale-yang-lsp|
+  yara....................................|ale-yara-options|
+    yls...................................|ale-yara-yls|
   zeek....................................|ale-zeek-options|
     zeek..................................|ale-zeek-zeek|
   zig.....................................|ale-zig-options|

supported-tools.md

@@ -746,6 +746,8 @@ formatting.
   * [yq](https://github.com/mikefarah/yq)
 * YANG
   * [yang-lsp](https://github.com/theia-ide/yang-lsp)
+* Yara
+  * [yls](https://github.com/avast/yls)
 * Zeek
   * [zeek](http://zeek.org) :floppy_disk:
 * Zig

test/linter/test_yara_yls.vader

@@ -0,0 +1,13 @@
+Before:
+  call ale#assert#SetUpLinterTest('yara', 'yls')
+
+After:
+  call ale#assert#TearDownLinterTest()
+
+Execute(The default executable path should be correct):
+  AssertLinter 'yls', ale#Escape('yls') . ' -v'
+
+Execute(The project root should be detected correctly):
+  call ale#test#SetFilename('../test-files/yara/dummy.yar')
+
+  AssertLSPProject ale#path#Simplify(g:dir . '/../..')

test/test-files/yara/dummy.yar

@@ -0,0 +1,5 @@
+rule dummy
+{
+    condition:
+        false
+}