feature #30826 [Form] Add file links for described classes in debug:form command (yceruto)

This PR was merged into the 4.3-dev branch.

Discussion
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[Form] Add file links for described classes in debug:form command

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT

![debug_form_file_link](https://user-images.githubusercontent.com/2028198/55357775-d1eac980-549b-11e9-8aa8-500aee629753.png)

Commits
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dcba01d212 Add file links for described classes

Author: fabpot

Resources/config/console.xml

@@ -160,6 +160,7 @@
             <argument type="collection" /> <!-- All services form types are stored here by FormPass -->
             <argument type="collection" /> <!-- All type extensions are stored here by FormPass -->
             <argument type="collection" /> <!-- All type guessers are stored here by FormPass -->
+            <argument type="service" id="debug.file_link_formatter" on-invalid="null" />
             <tag name="console.command" command="debug:form" />
         </service>
     </services>