Add per-session OP-TEE client identity handling

[sangho2]

This PR adds support for handling OP-TEE client identity per session not per instance. Default client identity is now Public not User. It also does some additional sanity checks.

[sangho2]

We should merge #865 first because this PR should have one more fix: per-session ClientIdenty rather than per-instance ClientIdentity. #865 heavily refactored related data structures and functions.

[github-actions]

🤖 SemverChecks 🤖 ⚠️ Potential breaking API changes detected ⚠️

Click for details

--- failure enum_variant_added: enum variant added on exhaustive enum ---

Description:
A publicly-visible enum without #[non_exhaustive] has a new variant.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#enum-variant-new
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.48.0/src/lints/enum_variant_added.ron

Failed in:
  variant TeeLogin:ReeKernel in /home/runner/work/litebox/litebox/litebox_common_optee/src/lib.rs:859

--- failure inherent_method_missing: pub method removed or renamed ---

Description:
A publicly-visible method or associated fn is no longer available under its prior name. It may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.48.0/src/lints/inherent_method_missing.ron

Failed in:
  OpteeShimEntrypoints::get_session_id, previously in file /home/runner/work/litebox/litebox/target/semver-checks/git-main/57bd142707cd1f41b3b99c75722ba483bb394692/litebox_shim_optee/src/lib.rs:328

--- failure method_parameter_count_changed: pub method parameter count changed ---

Description:
A publicly-visible method now takes a different number of parameters, not counting the receiver (self) parameter.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#fn-change-arity
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.48.0/src/lints/method_parameter_count_changed.ron

Failed in:
  litebox_shim_optee::OpteeShim::load_ldelf takes 5 parameters in /home/runner/work/litebox/litebox/target/semver-checks/git-main/57bd142707cd1f41b3b99c75722ba483bb394692/litebox_shim_optee/src/lib.rs:232, but now takes 3 parameters in /home/runner/work/litebox/litebox/litebox_shim_optee/src/lib.rs:238