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.

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

test/test-files/yara/dummy.yar

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