Various code cleanups for the new shortcut entity

I've made it applicable.

1. +++ b/core/modules/shortcut/lib/Drupal/shortcut/Form/SetCustomize.php
   @@ -17,30 +17,11 @@
   +  protected $entity;
   ...
   +   * The entity being used by this form.
   ...
   +   * @var \Drupal\shortcut\ShortcutSetInterface
   

   Should be removed because defined in EntityFormController

2. +++ b/core/modules/shortcut/lib/Drupal/shortcut/ShortcutFormController.php
   @@ -22,56 +16,11 @@
   +   * The entity being used by this form.
   ...
   +   * @var \Drupal\shortcut\ShortcutInterface
   ...
   +  protected $entity;
   

   the same here

3. +++ b/core/modules/shortcut/lib/Drupal/shortcut/ShortcutFormController.php
   @@ -83,7 +32,7 @@ public function form(array $form, array &$form_state) {
   -      '#default_value' => $entity->title->value,
   +      '#default_value' => $entity->getTitle(),
   

   Suppose better to use $this->entity here and remove previous $entity = $this->entity - the scope allows

4. --- a/core/modules/shortcut/lib/Drupal/shortcut/Entity/Shortcut.php
   +++ b/core/modules/shortcut/lib/Drupal/shortcut/Entity/Shortcut.php
   
   @@ -10,7 +10,7 @@
   - * Provides an interface defining a shortcut entity.
   + * Provides an interface defining a shortcut_set entity.
   

   s/shortcut_set/shortcut set

   The same should apply for ShortcutSet.php entity unit

Great! About 1 & 2 lets get commiter's feedback

Re-roll, because the shortcut entity's link template was fixed already.

back to rtbc

drupal_2156923_11.patch no longer applies.

error: patch failed: core/modules/shortcut/lib/Drupal/shortcut/Entity/Shortcut.php:10
error: core/modules/shortcut/lib/Drupal/shortcut/Entity/Shortcut.php: patch does not apply

Made changes and rerolled the patch.

#16 is a reroll of #11. I steped jayeshanandani through the process while also rerolling it myself. Our patches are identical, so RTBC.

2156923.16.patch no longer applies.

error: patch failed: core/modules/shortcut/lib/Drupal/shortcut/Entity/Shortcut.php:10
error: core/modules/shortcut/lib/Drupal/shortcut/Entity/Shortcut.php: patch does not apply

Rerolled the patch. Merged without any conflicts.

Just uploading the same patch since the testbot did not pick it up.

rtbc since it was rtbc'd by @ianthomas_uk and the latest reroll was an easy automatic one.
I also gave the patch a quick look and nothing jumped out at me to make it needs work.

Committed 0f56bfa and pushed to 8.x. Thanks!