Fix default landing page is not considered in clients listing

[xispa]

Description of the issue/feature this PR addresses

This Pull Request fixes the default landing page when a client from the folder listing is selected as well as when a client login the system and no default wide landing page is set in classic setup.

This functionality was once provided by means of the registry record with key bika.lims.client.default_landing_page, that is no longer available in 2.x instances, but in those upgraded from 1.x

The setting is now available under SENAITE Registry:

Current behavior before PR

The legacy setting for the default landing page is no longer used

Desired behavior after PR is merged

The legacy setting for the default landing page is ported to SENAITE registry

--
I confirm I have tested this PR thoroughly and coded it according to PEP8
and Plone's Python styleguide standards.

[xispa]

This whole dance is not worth. Closing

[xispa]

Re-opening this one because of legacy compatibility. We'll need to revisit this landing page thing at some point though.

[ramonski]

Thanks Jordi!
Just one thing:
Can you move the key "client_landing_page" into the config as a variable?

[ramonski]

Please also add our @upgradestep(product, version) decorator around the import_registry function. I've seen that add-ons might loose the navigation settings.

[xispa]

Thanks Jordi! Just one thing: Can you move the key "client_landing_page" into the config as a variable?

Done with 6f6f89d

[xispa]

Please also add our @upgradestep(product, version) decorator around the import_registry function. I've seen that add-ons might loose the navigation settings.

Done with e4926a5