Log a warning if attribute names contain a space

Working on it.

Added a logger, please check.

Added test,
@smustgrave please review.

Hey, I am Gautham, at DrupalCon Atlanta, and I am working on testing this

Putting into NW as the pipeline has issues. But maybe someone from DrupalCon will pick up.

@arunsahijpal can you add the steps to reproduce this issue?

Also, I noticed there is a commit related to another issue(#3514939) in this merge request, can you provide some clarification on why it was part of this merge request?

Hi @grallapa2,
As this issue in not like other issues which you can reproduce as I.S says that if you write a wrong attribute name in an element then the drupal just strips it silently without informing the user that he/she has used a wrong attribute so in order to follow a good practice we are going to log a warning before stripping the attribute.
So I've added a logger warning and a test case to check this.

For running this testcase you can do

phpunit core/tests/Drupal/Tests/Core/Template/AttributeTest.php

and if you want to do manual testing on your cli then you may write this

 drush php:eval ' 
  $attributes = new \Drupal\Core\Template\Attribute([
    "valid_attribute" => "value",
    "invalid attribute" => "value",
  ]); 
  dump($attributes->toArray()); 
  \Drupal::logger("debug")->notice("Attributes stored: @attributes", ["@attributes" => json_encode($attributes->toArray())]); 
'

and that issue no. mentioned in that commit is done by mistake, could you please correct it?

Feel free to ask any other query.

Thanks,
Arun