hls-explicit-imports-plugin: Add golden files to hackage tarball (#2373)

Author: maralorn

plugins/hls-explicit-imports-plugin/hls-explicit-imports-plugin.cabal

@@ -10,7 +10,10 @@ author:             Pepe Iborra
 maintainer:         [email protected]
 category:           Development
 build-type:         Simple
-extra-source-files: LICENSE
+extra-source-files:
+  LICENSE
+  test/testdata/*.hs
+  test/testdata/*.yaml
 
 library
   exposed-modules:    Ide.Plugin.ExplicitImports