The new datastore PR now has a generation count; this passes
the tests against that now.
Also copies tests from c-lightning, and adds ugprade test.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
See https://github.com/ElementsProject/lightning/pull/4674
(I manually tested that it passes all the tests there, too!)
When they finally upgrade the node, this automatically puts any
datastore data into the inbuilt datastore and shuts down.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
