CLI tests

Live under crates/ethercat-esi-cli/tests/.

Test Case: cargo esi expand emits a single device's code TEST_0450
status: open
verifies: REQ_0550

Spawn the CLI as cargo esi expand --device EL3001 --glob <fixtures>/*.xml, capture stdout, assert the output is non-empty, parses as Rust, and contains exactly one pub struct EL3001 definition.
Test Case: cargo esi list enumerates devices TEST_0451
status: open
verifies: REQ_0551

Run cargo esi list --glob <fixtures>/*.xml over a 3-device fixture set, assert stdout contains 3 lines each matching the <ident>\t<vendor_id>\t<product_id>\t<revision> format.
Test Case: CLI output matches build helper output byte-for-byte TEST_0452
status: open
verifies: REQ_0552

For one fixed device, capture the CLI’s expand output and the build helper’s per-device slice of $OUT_DIR/devices.rs. Assert the two byte-strings are identical (catches divergent code paths between CLI and build).