formatter: fill missing resources by formatter, not by resource mapper While working on demand loading of ctx/fctx objects, I found it's weird to support lookup in both directions. For instance, fctx can be loaded from (ctx, path) pair, but ctx may also be derived from fctx.changectx() in the original mapping. If the original mapping has had fctx but no ctx, and if the new mapping provides {path}, we can't be sure if fctx should be updated by fctx'.changectx()[path] or not. This patch simply drops the support for the resolution in fctx -> ctx -> repo direction.