migration30: add supporting functions to help with unit tests
migration30: add supporting functions to help with unit tests

This commit adds supporting functions that will be used in the unit
test. The testing data are also added as hard-coded. We choose to copy
the most of the testing data from our itest results such that a) they
are "real" data that can be used to calculate scripts and b) we preserve
the result generated by the current code so a future change won't affect
our test.

aakselrod/lnd,aakselrod/lnd