implement testing framwork

[arhabd]

create a section with a testing framework so board testers all test the same set of functions in the heads firmware where certain sections might differ if they are not tested and a board tester just does unsafe usb boot thats not making sure tpm working like it should for example

// todo take insperation from https://github.com/linuxboot/heads/pull/1913#issuecomment-2669323555