Port SeaBIOS PCI oprom extraction in ram + measurement + load into coreboot

[tlaurion]

Chainloading seabios -> linux payload would not be desired since seabios would actually lower security model.

What is desired is seabios extraction of oprom in ram, measuring it then loading it.

Discussed under https://matrix.to/#/!rsKWMJGPMsyPTTjXuh:matrix.org/$tfmbWeuklG258ig33TJMsVSdTvOosR7DvdodjyD_y9I?via=matrix.org&via=nitro.chat&via=fedora.im

Originally posted by @tlaurion in https://github.com/linuxboot/heads/issues/1752#issuecomment-2343938844