safety: add body safety tests

[sshane]

Split from #1699

• Added address check for CAN flasher - referenced from commaai/body@1fc01d7#diff-bcec6c3a8fbf0fa79219486d3b495204d8f58664feafeecdc27f0efa2592a4bb
• Made controls allowed logic more explicit, valid never goes false after first valid message.
• Check address so not any message causes controls_allowed to rise

Will test on body to make sure these bugs weren't being relied on to work