EZP-23368: Migrated "border" filter.
EZP-23368: Added filter/noise filter loader
EZP-23368: Added comment on why "flatten" filter has been discarded
EZP-23368: Added info about resize filter
EZP-23368: Added colorspace/gray filter loader
EZP-23368: Added filter/swirl filter and loader.
EZP-23368: Ensure filters and loaders are private services
EZP-23368: Added BC doc
Merge pull request #1010 from ezsystems/impl_EZP-23368_legacyImageFiltersMigration

Fix EZP-23368: Migrate image filters leftovers