feature #24064 [TwigBridge] Show Twig's loader paths on debug:twig command (yceruto)
feature #24064 [TwigBridge] Show Twig's loader paths on debug:twig command (yceruto)

This PR was squashed before being merged into the 3.4 branch (closes #24064).

Discussion
----------

[TwigBridge] Show Twig's loader paths on debug:twig command

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

`bin/console debug:twig`:
![twig-loader-paths](https://user-images.githubusercontent.com/2028198/29986784-ee5a4094-8f32-11e7-86c8-c78183630221.png
)

This information is not displayed anywhere ATM and it should be important to know:
 * The Twig's namespaces availables
 * The Twig's paths availables
 * The order that templates will be loaded ( regarding its namespace -> LOAD PRIORITY ! )

So it should help us to debug any issue related to circular templates reference, invalid namespaces, unsuccessful attempt to override a template, etc.

WDYT?

Commits
-------

3fdcb40df3 [TwigBridge] Show Twig's loader paths on debug:twig command

symfony/twig-bundle,symfony/twig-bundle