Refactor/Enhance AttributeServers (#240)
* Refactor AttributeServers to fully support getter, setter and validator functions
* Wire in new methods
* Correct usage set -> setLocal
* integrate updates for existing "getter based attributes"
* Add fabric scoped read of fabrics attribute
* Add reading for more getter based methods in OperationalCredentialsCluster
* We need to detect "fixed" differently because of new inheritance
* Adjust set/get -> seLocal/getLocal in more places, enhance tests
* tests
* Optimizations and tests
* remove todo because migrated
* access to rootcert
* add access to omitChanges for subscriptions
* Finalize tests
* Finalize tests
* fixes
* test fixes
* Add FabricIndex data changes from @lauckhart
* Enhance Tlv classes to allow Field injection and removal based on Field IDs
* Move Array chunk support to Schema classes too (and add chunking incl. tests)
* rename method to better suit for client and server usage
* Allow session access for InteractionClient to know session fabric
* Enhance FabricIndex and allow to specify OMIT_FABRIC for write calls without the field
* AttributeServer refactoring
* AttributeClient refactoring
* More missing set->setLocal
* Fixes and add support for fabricFiltered read of nocs and trusted Certs
* Adjust tests
* FabricIndex to spec
* Changelog
* final test fixes
* Refactor AttributeServer based on review feedback
* Allow to catch non-associated-fabric error
* add assert for secure session
* adjust getter for session and name attributes
* add assert method for secure session
* Separate validation errors
* todos and typo
* latest adjustments from Attributeserver refactoring
* Adjust tests
* changelog
* gitignore . files
* added todo
