chore: add tools/list integration test

[mrizzi]

First and very basic test to list the tools available for the MCP server, done first of all to have a test approach for the MCP Server (replacing the simple cargo build executed previously).

It doesn't require any running trustify instance but for sure it's something that must be added soon to develop more tests that interact with trustify.

In an effort or reusing contains_subset from trustify, I faced this error:

error: environment variable `CARGO_WORKSPACE_ROOT` not defined at compile time
   --> /Users/mrizzi/.cargo/git/checkouts/trustify-094e5444376295b1/dd6f240/test-context/src/lib.rs:201:35
    |
201 |     let workspace_root: PathBuf = env!("CARGO_WORKSPACE_ROOT").into();
    |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: Cargo sets build script variables at run time. Use `std::env::var("CARGO_WORKSPACE_ROOT")` instead

error: could not compile `trustify-test-context` (lib) due to 1 previous error

so I've pushed the branch chore-env-not-defined with the fix (?) that, before merging this PR, should be properly discussed and fixed in trustify itself.

[mrizzi]

contains_subset fixed adding .cargo/config.toml in 3fb3046 just like trustify project has it (ref. config.toml)