src/test/osd: remove tmap test

Signed-off-by: Samuel Just <sam.just@inktank.com>
test/osd/Object: create encoders for ContDesc

Signed-off-by: Samuel Just <sam.just@inktank.com>
src/test/osd: restructure Object/RadosModel in prep for append

Attribute handling no longer has special support in ContentsGenerator.
The most recent operation information is now stored in a special
attr rather than at the beginning of the object.  ObjectDesc layers
include their own ContentsGenerators to allow more flexibility.

Also, writes truncate to the new object size rather than simply
causing reads to stop at that object size.

Signed-off-by: Samuel Just <sam.just@inktank.com>
src/test/osd: adapt RadosModel to not do omap ops on ec_pools

Signed-off-by: Samuel Just <sam.just@inktank.com>
src/test/osd: add append support to WriteOp

Signed-off-by: Samuel Just <sam.just@inktank.com>
working