Fix EZP-23387: Move image variation config for ezdemo to DemoBundle

Also fixes EZP-23382.
See https://github.com/ezsystems/ezpublish-kernel/pull/1069
EZP-22324: BDD tests for premium content
Fix EZP-22839: DemoBundle settings hardcoded to specific siteaccess names/group

> https://jira.ez.no/browse/EZP-22839

Changed `ezdemo_frontend_group` to `default`.
This was not possible before since `default` keyword wasn't taken into
account in semantic config.

Also added pagelayout configuration for legacy to its own file, using
semantic configuration for EzLegacyBundle. Thus
`ezpublish.default.view_default_layout` should be removed from default
`parameters.yml.dist`.
Fix EZP-23622: Link for "For more options try the advanced search" in DemoBundle loses words
Merge pull request #122 from pedroresende/EZP-23622

Fix EZP-23622: Link for "For more options try the advanced search" in DemoBundle loses words
Add ".idea" folder to gitignore file
Merge pull request #123 from sdaoudi/master

Add ".idea" folder to gitignore file
Fix EZP-23600: productimage image_variation injection missing reference
and filters in admin interface
Implemented premium subscriber content

A custom location view provider displays a teasing template
if the content is Premium (section id 7 (Premium)), and if the
user doesn't have the subscriber role (id: 6)

section_id and role_id are configured in default_settings.yml.
Merge branch 'EZP-22324-premium_content_bdd' into EZP-22324-premium_content