Achieve compatability with JSON:API 1.1

[Art4]

Closes #90.

TODO

• Allow new lid property in Resource Objects https://jsonapi.org/format/1.1/#document-resource-objects
• Allow new lid property in Resource Identifier Objects https://jsonapi.org/format/1.1/#document-resource-identifier-objects
• Allow new ext and profile properties in Jsonapi object https://jsonapi.org/format/1.1/#document-jsonapi-object
• Allow new describedby property in the top level Links object https://jsonapi.org/format/1.1/#document-top-level
• Allow new possible members in top level Object defined by an extension https://jsonapi.org/format/1.1/#document-top-level
• Allow new possible member in Relationship Objects defined by an extension https://jsonapi.org/format/1.1/#document-resource-object-relationships
• Allow new possible member in Relationship Link Objects defined by an extension https://jsonapi.org/format/1.1/#document-resource-object-relationships
• Allow Links containing a string (instead of an object) https://jsonapi.org/format/1.1/#document-links
• Allow Link Objects containing new members like rel, title, describedby, type and hreflang https://jsonapi.org/format/1.1/#auto-id--link-objects
• Allow new @-Members https://jsonapi.org/format/1.1/#document-member-names-at-members
• Allow new header member in Error Source objects https://jsonapi.org/format/1.1/#error-objects

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (d156fb4) to head (19df2d6).

Additional details and impacted files

@@             Coverage Diff             @@
##                v1.x       #96   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
+ Complexity       298       292    -6     
===========================================
  Files             29        29           
  Lines            627       625    -2     
===========================================
- Hits             627       625    -2     

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