refactor pvf security module (#3047)

resolve https://github.com/paritytech/polkadot-sdk/issues/2321

- [x] refactor `security` module into a conditionally compiled
- [x] rename `amd64` into x86-64 for consistency with conditional
compilation guards and remove reference to a particular vendor
- [x] run unit tests and zombienet

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Co-authored-by: s0me0ne-unkn0wn <[email protected]>