Merge #11303: Fix estimatesmartfee rounding display issue

Merge #11303: Fix estimatesmartfee rounding display issue

1789e4675 Force explicit double -> int conversion for CFeeRate constructor (Matt Corallo)
53a6590f4 Make float <-> int casts explicit outside of test, qt, CFeeRate (Matt Corallo)
0b1b9148c Remove countMaskInv caching in bench framework (Matt Corallo)

Pull request description:

  This fixes an issue where estimatesmartfee which matches at the min relay fee will return 999 sat/byte instead of 1000 sat/byte due to a float rounding issue. I went ahead and made all float <-> int conversion outside of test/qt explicit (test only had one or two more, Qt had quite a few, including many in the Qt headers themselves) and added overloads to CFeeRate to force callers to do an explicit round themselves. Easy to test with -Wfloat-conversion.

Tree-SHA512: 66087b08e5dfca67506da54ae057c2f9d86184415e8fa4fa0199e38839e06a3ce96c836fcb7593b7d960065f5240c594ff3a0cfa14333ac528421f5aeac835c9