Fix EZP-23408: use correct scope 'image' for images in legacy IO handler
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
Merge pull request #1012 from joaoinacio/EZP-23408_dfs_image_scope

Fix EZP-23408: use correct scope 'image' for images in legacy IO handler
IO: Removed InMemory handler
IO: de-duplicated services
IO: Added custom factory method for filesystem handler
IO: added EzPublishIOBundle with configuration

The "main" io handler service is now always used,
and is dynamically built depending on the semantic config.

The ezpublish_io.handler tag is added, with an alias property for the name of the handler.
IO: made filesystem the default handler
IO: Removed unused IO config parser
Fixed review remarks
Moved IOFactory to IOBundle
IO: Added ezpublish.io_handler tag pass tests