Class amount_msat

plugins/renepay/test/run-testflow.c:411–411

	const double eps = 1e-8;

	struct amount_msat min = AMOUNT_MSAT(10); // known min
	struct amount_msat max = AMOUNT_MSAT(19); // known max

	struct amount_msat X = AMOUNT_MSAT(0); // in flight