SDK, reorganize mod structure for clarity

[jul-sh]

Moves a couple of utility functions from the root level into a pub channel and utils mod. Should make the docs a lot easier to read. Also aligns the crate file structure with its pub interface for clarity.

The diff is a bit misleading, but code has only been moved between files, not written anew.

This is technically a breaking change, but all moved functions are very new, and I don't expect teams to already be depending on them. And if they are, the compiler error message should make migration not too difficult.

[andrisaar]

Proposal: move all the mock attestation related stuff into mock_attestation.rs or something like that.

This would leave the root lib.rs much cleaner, and mean you'd only have to tag mod mock_attestation with the feature gate.

(Honestly I'd probably move all the non-mock stuff to a different file as well, keeping only the interfaces in the root lib.rs file.)

[tiziano88]

Proposal: move all the mock attestation related stuff into mock_attestation.rs or something like that.

This would leave the root lib.rs much cleaner, and mean you'd only have to tag mod mock_attestation with the feature gate.

(Honestly I'd probably move all the non-mock stuff to a different file as well, keeping only the interfaces in the root lib.rs file.)

+1 all the mock stuff is quite invasive at the moment, a sub module may make that tidier

[jul-sh]

I've moved the attestation structs to instance_attestation and mock_attestation submodules respectively. I agree it makes the crate a lot more readable.

@tiziano88 @ipetr0v What do you both think? Imo this seems nice, but then the struct naming becomes a bit redundant.

eg:

oak_restricted_kernel_sdk::mock_attestation::MockEvidenceProvider,

etc. Should we shorten the struct names? (imo probs yes). Should instead we keep it all in one mod? Many choices.

[ipetr0v]

I've moved the attestation structs to instance_attestation and mock_attestation submodules respectively. I agree it makes the crate a lot more readable.

@tiziano88 @ipetr0v What do you both think? Imo this seems nice, but then the struct naming becomes a bit redundant.

eg:

oak_restricted_kernel_sdk::mock_attestation::MockEvidenceProvider,

etc. Should we shorten the struct names? (imo probs yes). Should instead we keep it all in one mod? Many choices.

I don't think we'll ever have a Group Attestation, so the instance attestation name may be confusing. So maybe just attestation?

Also I think MockAttestation also be moved to tests or testing, since it will only used for tests.

[jul-sh]

I don't think we'll ever have a Group Attestation, so the instance attestation name may be confusing. So maybe just attestation?

Idk, seems possible we may want that at some point

Also I think MockAttestation also be moved to tests or testing, since it will only used for tests.

like public testing module? It needs to be public, since it's exported for to be used by other crates in their tests