[nextjs] Render FEaaS components server side

[art-alexeyenko]

Ensure feaas-component can generate server markup as well as client one.

• This PR follows the Contribution Guide

Description / Motivation

FEaaS wrapper would only add a client component previously - so all the rendering would be done client-side.
With this change we support FEaaS wrapper generating server markup. At the same time there's a fallback to only generate client component when required server props are missing.

It also includes a rework of how it handles extra data (i.e. fields are no longer a part of props), but perhaps it needs to be reintroduced.

Testing Details

• Unit Test Added
• Manual Test/Other (Please elaborate) - tested with connected, production mode

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[Inviz]

Seems like a solid work. Thanks Artem for working through the kinks with me, your help is very appreciated.

[illiakovalenko]

Good work! Please, see review comments below

[ambrauer]

Looks like we lost use of Sitecore datasources (code which reads datasource component fields was removed). Based on the PR description, this was intentional. Is there more coming to bring this back? Or is this now somehow built in to the FEAAS SDK?

[ambrauer]

Just one last thought. Otherwise, looks good to me

[illiakovalenko]

@art-alexeyenko Please, add note to CHANGELOG file and see comments above + unresolved comments