Move the deprecated updateLinksOnFarm APIs of the refactoring requests to legacy

The updateLinksOnFarm accessors of DeleteRequest and AbstractCopyOrMoveRequest, and the DeleteRequest.UPDATE_LINKS_ON_FARM constant, have been deprecated since 14.8RC1 and are no-ops (the flag is not taken into account anymore). Nothing in xwiki-commons, xwiki-rendering or xwiki-platform uses them.

Move them to xwiki-platform-legacy-refactoring-api, which already weaves xwiki-platform-refactoring-api, so that the main module no longer exposes them while existing extensions keep working with the legacy module (distributed by default).

• The methods are re-added by AspectJ inter-type declarations.
• The constant is re-added through a CompatibilityDeleteRequestConstants interface that the aspect makes DeleteRequest implement, since a static final field added by an aspect is neither final nor a compile-time constant.
• AbstractCopyOrMoveRequest gets an explicit serialVersionUID, required by AspectJ to add public methods to a serializable class.