Normalize whitespace in source files

Ensure that no source files have trailing whitespace at end of lines and ensure that all files end with a single trailing newline.

This also adds Github Actions to enforce whitespace conventions.

src-ui/src/app/data/paperless-saved-view.ts

@@ -15,4 +15,4 @@ export interface PaperlessSavedView extends ObjectWithId {
 
   filter_rules: FilterRule[]
 
-}
+}