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/components/document-list/document-card-large/document-card-large.component.scss

@@ -64,4 +64,4 @@
 span ::ng-deep .match {
   color: black;
   background-color: rgb(255, 211, 66);
-}
+}

src-ui/src/app/components/document-list/filter-editor/filter-editor.component.html

@@ -3,7 +3,7 @@
      <div class="form-inline d-flex align-items-center">
          <div class="input-group input-group-sm flex-fill w-auto">
            <div class="input-group-prepend" ngbDropdown>
-            <button class="btn btn-outline-primary" ngbDropdownToggle>{{textFilterTargetName}}</button>   
+            <button class="btn btn-outline-primary" ngbDropdownToggle>{{textFilterTargetName}}</button>
             <div class="dropdown-menu shadow" ngbDropdownMenu>
               <button *ngFor="let t of textFilterTargets" ngbDropdownItem [class.active]="textFilterTarget == t.id" (click)="changeTextFilterTarget(t.id)">{{t.name}}</button>
             </div>