Test strategy for our providers on the CI

[hug-dev]

I think it could be tested by changing nothing but having a different configuration file which points to the SoftHSM library. There is an available Dockerfile that installs the library that we can use.

I think we also have to think how we are going to scale testing of multiple providers on the CI.

I was thinking of having single provider tests (our current tests) and multiple providers tests that test more the configuration as opposed to a provider implementation. For that purpose we should have multiple configuration files for all of those cases: one per provider and another one including them all.

[hug-dev]

We could add an optional argument when launching Parsec to specify a configuration file path and use this one. That way we can have in-tree one configuration file per provider and test them independently 😄

And one more with all of them 😈

[hug-dev]

We would have the following test structure (in tests):

all.sh -> Executing all of the tests below + rustfmt + clippy (will work only if everything is installed)
per_provider/ -> Test executed only with a single provider
    normal/
    stress/
    fuzz/
    persistence/
    PROVIDER_NAME/ -> Folder containing the Dockerfile and config.toml file per provider
        Dockerfile
        config.toml
all_providers/ -> Tests using all providers
    Dockerfile -> Would contain all providers (not published)
    config.toml
    mod.rs
cross_compilation/ -> Testing cross compilation of Parsec
    Dockerfile
    Cross.toml

The following Dockerfile would be needed:

1. one for the TPM provider + tss-esapi crate (there is one in parallaxsecond/rust-tss-esapi repo already)
2. one for the PKCS 11 provider
3. one for the Mbed Crypto provider + crate (cf Create a PSA Crypto Rust wrapper crate #62)
4. one combining 1, 2 and 3 for the all_providers tests
5. one for cross-compilation, that already exists

Exactly the same tests (except cross_compilation) could be done on an Arm platform, on the CI, check #55 to also have coverage for Arm.