Provide sample programs for PSA APIs

[gilles-peskine-arm]

Provide sample programs for PSA Crypto APIs.

The scope isn't defined precisely: we don't need sample code for every single function, but we need the most common use cases.

Hannes has already written PSA sample programs in #5064. We need to upstream them as has been done for the hash program in #7942.

The programs should be added to all branches where the relevant functions exist, not just to development, since the lack of sample programs is a long-standing defect that 4.0 is just making more acute.

Note: this is a large task which should not be done in a single pull request. One sample program per pull request is a good pace.

[davidhorstmann-arm]

A note that this was previously work in progress by @tom-daubney-arm

[tom-daubney-arm]

I have split out #5064 into separate PRs and I have progressed them all locally and pushed some for review. Currently #7954 is waiting on review but has not been able to be prioritised yet due to other work.

The rest of the PRs are (which all need a bit of work):
#7953
#7951
#7948
#7944
#7938

Note that a small amount of work is needed to happen on the CI testing side for the example programs. Currently it is not possible to specify an "anti-dependency" i.e. a config option that needs to be switched off in order for the program to run. I have implemented a solution locally (not pushed anywhere) that allows us to specify anti-dependencies for the program in the CI scripts by prepending an "!" to the config option name, like we do in the main test framework. I can raise a separate PR for this.