Enable twig namespace 'theme' by default in order to easily use custo…

[iamgoodbytes]

Enable twig namespace theme by default in order to use this to overwrite templates more easily out of the box with bolt/forms.

This PR is linked to bolt/forms#18 in bolt/forms

cc @I-Valchev

[bobdenotter]

👍

[bobdenotter]

This actually breaks the installation process:

Run composer recipes at any time to see the status of your Symfony recipes.
Executing script cache:clear --no-warmup [KO]
 [KO]
Script cache:clear --no-warmup returned with error code 1
!!
!!  In FilesystemLoader.php line 92:
!!
!!    The "/Users/bob/Sites/Bolt/myprojectname/public/theme/base-2021" directory
!!    does not exist ("/Users/bob/Sites/Bolt/myprojectname/public/theme/base-2021
!!    ").
!!

I'll see if i can workaround it.

[bobdenotter]

I had to revert this for now, because it broke the installation process: 2b91bba

Let's see if we can find a better solution for this, @I-Valchev