Fix various nullability related issues

Cleared interfaces and implementing classes to properly deal with nullability annotations in Headless Server.

(CMS-19701)

[Headless] Exposing Missing SEO Properties

The missing properties for CMLinkable "htmlTitle", "keywords" and "htmlDescription" were added to the content schema.

(CMS-19690)

Fix broken handling of arrays in input values for headless persisted queries and rest endpoint

Arrays passed as input values for the persisted queries and the rest endpoint are now converted correctly and work as intended. With this it is also possible to pass arrays as parameters of queries.

(CMS-19689)

Support ContentBlobLinkComposer in RichText conversion

Added the ContentBlobLinkAdapterFactory to the EvaluationContext to be able to use the ContentBlobLinkComposer in RichTextConversion. Deprecated the old contstructors not providing the ContentBlobLinkAdapterFactory. In Order to use the ContentBlobLinkComposer in RichText conversion, you need to actually use the new constructors, this also happens currently by default in the CaasConfig.

(CMS-19520)

Fix ViewBySiteFilterDataFetcher not checking DataFetcherResults

The ViewBySiteFilterDataFetcher now also properly can deal with DataFetcherResults and not just accepts them.

(CMS-19517)

Non default values of configuration property 'caas-rest.jslt-transformations-pattern' were not used properly

The jslt transformation resouces *.jslt were always loaded from the default location. A configuration value of ''caas-rest.jslt-transformations-pattern' different from the default was not used properly.

(CMS-19303)

Configuration of custom Solr fields

Custom Solr fields can be configured for the Headless-Server to be used in Search or QueryLists. See documentation for details.

(CMS-19277)

Headless Server sends HTTP header Strict-Transport-Security by default

Headless Server now sends by default a Strict-Transport-Security HTTP header with the default value of "max-age= 63072000; includeSubdomains". The content of the header can be configured by application properties. Please see the deployment manual for details.

(CMS-19046)