CI: check if most text files have final_newline and conform to editorconfig (MR 3530)

fixes #592

.editorconfig

@@ -7,8 +7,8 @@
 # Top-most EditorConfig file.
 root = true
 
-[**/APKBUILD]
+[{**.{md,ini,sh,rules,nft},**/APKBUILD}]
 indent_style = tab
 end_of_line = lf
-insert_final_newline = true
 trim_trailing_whitespace = true
+insert_final_newline = true

.gitlab-ci.yml

@@ -61,6 +61,15 @@ shellcheck:
   script:
     - .ci/shellcheck.sh
 
+editor-config:
+  stage: lint
+  <<: *only-default
+  image: alpine:edge
+  before_script:
+    - apk -q add editorconfig-checker
+  script:
+    - ec
+
 # aports checks (generic)
 aports-static:
   stage: lint