scripted-diff: test: Use int from_bytes and to_bytes over struct packing

-BEGIN VERIFY SCRIPT-
 sed -i --regexp-extended 's!struct.unpack\("(|<|>)B", (.*)\)\[0\]!int.from_bytes(\2, "little")!g'               ./test/functional/test_framework/messages.py
 sed -i --regexp-extended 's!struct.unpack\("<(H|I|Q)", (.*)\)\[0\]!int.from_bytes(\2, "little")!g'              ./test/functional/test_framework/messages.py
 sed -i --regexp-extended 's!struct.unpack\("<(h|i|q)", (.*)\)\[0\]!int.from_bytes(\2, "little", signed=True)!g' ./test/functional/test_framework/messages.py
 sed -i --regexp-extended 's!struct.unpack\(">(H|I|Q)", (.*)\)\[0\]!int.from_bytes(\2, "big")!g'                 ./test/functional/test_framework/messages.py

 sed -i --regexp-extended 's!struct.pack\("<?B", (.*)\)!\1.to_bytes(1, "little")!g'             ./test/functional/test_framework/messages.py
 sed -i --regexp-extended 's!struct.pack\("<I", (.*)\)!\1.to_bytes(4, "little")!g'              ./test/functional/test_framework/messages.py
 sed -i --regexp-extended 's!struct.pack\("<i", (.*)\)!\1.to_bytes(4, "little", signed=True)!g' ./test/functional/test_framework/messages.py
 sed -i --regexp-extended 's!struct.pack\("<Q", (.*)\)!\1.to_bytes(8, "little")!g'              ./test/functional/test_framework/messages.py
 sed -i --regexp-extended 's!struct.pack\("<q", (.*)\)!\1.to_bytes(8, "little", signed=True)!g' ./test/functional/test_framework/messages.py
 sed -i --regexp-extended 's!struct.pack\(">H", (.*)\)!\1.to_bytes(2, "big")!g'                 ./test/functional/test_framework/messages.py
-END VERIFY SCRIPT-

Author: MarcoFalke