This allows us to reference assumeutxo configuration by blockhash as
well as height; this is helpful in future changes when we want to
reference assumeutxo configurations before the block index is loaded.
These files change infrequently, and not much header shuffling is required.
We don't add everything in src/util/ yet, because IWYU makes some
dubious suggestions, which I'm going to follow up with upstream.
Added are:
* Vector(arg1,arg2,arg3,...) constructs a vector with the specified
arguments as elements. The vector's type is derived from the
arguments. If some of the arguments are rvalue references, they
will be moved into place rather than copied (which can't be achieved
using list initialization).
* Cat(vector1,vector2) returns a concatenation of the two vectors,
efficiently moving elements when relevant.
Vector generalizes (and replaces) the Singleton function in
src/descriptor.cpp, and Cat replaces the Cat function in bech32.cpp
