Convert theme_system_config_form() to Twig

This one looks like it should be a theme suggestion on 'container' with no markup... or something else?

Not sure about what I'm doing :(

To quote from FormBuilder.php

    // If no #theme has been set, automatically apply theme suggestions.
    // theme_form() itself is in #theme_wrappers and not #theme. Therefore, the
    // #theme function only has to care for rendering the inner form elements,
    // not the form itself.
    if (!isset($form['#theme'])) {
      $form['#theme'] = array($form_id);
      if (isset($form_state['build_info']['base_form_id'])) {
        $form['#theme'][] = $form_state['build_info']['base_form_id'];
      }
    }

So yes, that should be the case that is 'form__system_config'. That would be a bigger change with it's own issue.
More like theme_wrapper suggestions for theme_form to replace this. And maybe all that needs is a test to say it works and a change record for all these theme_*_form functions?

This is the last theme function from system.module! #1987410: [meta] system.module - Convert theme_ functions to Twig

Can we just get this in RTBC and open up a follow up for that?

In the mean time, this needs the following doc changes:

1. +++ b/core/modules/system/system.module
   @@ -2865,22 +2866,6 @@ function theme_confirm_form($variables) {
   - * Returns HTML for a system settings form.
   
   +++ b/core/modules/system/templates/system-config-form.html.twig
   @@ -0,0 +1,16 @@
   + * Template for system config form.
   

   This should Likely say "Default theme implementation for a system settings form."
   @See docblock standards https://drupal.org/node/1823416

2. +++ b/core/modules/system/templates/system-config-form.html.twig
   @@ -0,0 +1,16 @@
   + * as its #theme callback.  Otherwise, by default, system config forms will be
   + * themed by theme_form().
   

   theme_form will still be used with this theme as a wrapper, it is always the wrapper for forms, this just deals provides a place to wrap the children of theme_form.

   Also should probably have the message from the theme function

   * By default this does not alter the appearance of a form at all,
   * but is provided as a convenience for themers."

I have made a reroll of the patch #4 and I have added the changes of the comment #7.

Here is the patch

Thanks for the quick turn around on those changes @jjcarrion. I still think it needs to be clear that theme_form is the theme_wrapper and that this doesn't replace theme_form(otherwise you'd see
tags in it). This is wrapping the children of theme_form.

If my brain could work today I could give you what to write but maybe you have some ideas on how it could be better written.

Also @jjcarrion what do you think about moving the consolidation to another issue for all theme_*_form() type functions that wrap the children of theme_from() to suggestions and just get this issue in?

Removing the need for profiling as this is admin facing and super simple. Just need a manual test to confirm this template is being used (though there should be no markup changes other than whitespace). Added steps to reproduce in the Issue Summary.

@joelpittet: What do you think about:

This template will be used when a system config form specifies 'config_form'
as its #theme callback. It's used to wrap theme_form() children. This does not
alter the appearance of a form at all, but is provided as a convenience for themers.

I'm mentoring @jjcarrion and he's interested in continue helping with this and the consolidation issue. So, should he create an issue for the rest theme_*_form() type functions and do the same work like in this issue? (Maybe I'm not understanding it well, sorry)

@rteijeiro I'm all for creating a separate issue for theme_*_form()!

Just for illustration this is the structure:

<form><-- START #theme_wrapper => theme_form

<-- START #theme => theme_system_config_form (empty space for wrappers around form children)

<label><input><-- form element children from {{ form }}
<label><textarea><-- form element children from {{ form }}

<-- ENDS theme_system_config_form

</form><-- ENDS theme_form

@rteijeiro and @jjcarrion here's an issue for you guys to go to town.
#2265991: Replace theme_*_form() with theme suggestion for #theme => form.

I hope I gave enough instructions for you to play with.

I have been testing this patch and I think that works ok. I have attached some screenshots:

/admin/appearance/settings
- without the patch (screenshot-2151821-before-patch.png)
- patch applied (screenshot-2151821-after-patch.png)
- patch applied with a custom template (screenshot-2151821-after-patch-using-my-template.png)

/admin/config/development/performance
- patch applied (screenshot-2151821-after-patch_second-example.png)

If it's needed more testing, please, let me know.

I think that is all we need. My other issue can still delete this template if it can get through reviews. But in the mean time this is RTBC. Thanks for the review.

#2265991: Replace theme_*_form() with theme suggestion for #theme => form.

removing tags

Hmm needs a re-roll.

Re-Rolled!

Thanks @JacobSanford and @steinmb. As I mentioned in #16 this can be consolidated later in #2265991: Replace theme_*_form() with theme suggestion for #theme => form.
But for now this will do.

Fixed the accidental comment revert. Back to RTBC.

Well that was easy. :)

Committed and pushed to 8.x. Thanks!