[messaging] MessageFolder no longer implements FilterableObject interface.

[messaging] MessageFolder no longer implements FilterableObject interface.

Due to introduction of AbstractFilter::isMatching(json) method, MessageFolder no
longer needs to implement FilterableObject interface, because folders are filtered
using new implementation.

+ Remove MessageFolder::isMatchingAttribute()
+ Remove MessageFolder::isMatchingAttributeRange()
+ MessageFolder no longer inherits from FilterableObject

[Verification] Code compiles.

Signed-off-by: Michal Michalski <m.michalski2@partner.samsung.com>
Change-Id: If208ce7c6bce999c2b6422e5a282f04f625e1af2