commands: add `rbfpsbt` command #1506

Job	Run time
linter	42s
linter_gui	5m 46s
unit_tests (1.54, ubuntu-latest)	4m 59s
unit_tests (1.54, macOS-latest)	8m 1s
unit_tests (1.54, windows-latest)	6m 36s
unit_tests (nightly, ubuntu-latest)	56s
unit_tests (nightly, macOS-latest)	2m 27s
unit_tests (nightly, windows-latest)	1m 32s
unit_tests_gui (1.65, ubuntu-latest)	6m 31s
unit_tests_gui (1.65, macOS-latest)	11m 55s
unit_tests_gui (1.65, windows-latest)	8m 25s
unit_tests_gui (nightly, ubuntu-latest)	2m 33s
unit_tests_gui (nightly, macOS-latest)	3m 32s
unit_tests_gui (nightly, windows-latest)	4m 12s
	1h 8m 7s

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