Add backend for DSVGO banner settings

[davisagli]

https://gitlab.kitconcept.io/kitconcept/distribution-kitconcept-website/-/work_items/46

This adds a control panel for configuring settings for the @kitconcept/volto-dsgvo-banner add-on. This PR is a draft because the frontend add-on still needs to be updated.

What's included

• registry settings (with same defaults as the existing Volto settings in kitconcept/volto-dsgvo-banner)
• dsgvo-settings control panel (for REST API / Volto)
• ISiteEndpointExpander to include the value of these settings in the @site endpoint
• Upgrade step
• Functional tests
• Fix locales (kitconcept.website domain rather than kitconcept.site, add missing DE translation)
• Fix default language setting (remove it from the default profile so it doesn't get overwritten during an upgrade)

To do

• Use a new release of volto-dsgvo-banner
• Docs (there's no infrastructure for this in the website distribution yet))

Screenshot

[Tishasoumya-02]

PR in dsgvo addon: kitconcept/volto-dsgvo-banner#55

[sneridagh]

@Tishasoumya-02 merged! Please continue with it.

@davisagli we don't add for now the ID of the tracker? I guess it's the next thing that we will need to customize.

[Tishasoumya-02]

Sorry! got confused with the other frontend PR for dsgvo
that it was complete so I closed this. But this was for backend stuff

[Tishasoumya-02]

Screenshots:

With the following control panel settings:

When show GDPR false:

[Tishasoumya-02]

@sneridagh , the dsgvo version in VLT is already updated in this PR kitconcept/volto-light-theme#833 and is in main branch now, it just needs a release then I'll update VLT here too .

[sneridagh]

@Tishasoumya-02 Release 8.0.0a29 was released and added in the website dist. Please continue rolling this up! Next is merge I guess! Could you please confirm that it works well and report back? Then we can merge.

[Tishasoumya-02]

@sneridagh yes, updated with main and works well , added screenshots above. We can merge this now

[sneridagh]

@Tishasoumya-02 @jnptk please let's continue the things to be done in the ticket in: #39