test: CON-1422 vetKD payload builder/verifier unit tests (#3886)

This PR adds unit tests for the new vetKD payload builder. Some unit
tests are still annotated with `#[should_panic(expected = "not yet
implemented")]`, as the current implementation doesn't call the correct
crypto endpoints to create and validate combined vetKD shares yet. This
will be added in a subsequent PR, at which point the annotation will be
removed.

rs/consensus/vetkd/BUILD.bazel

@@ -28,6 +28,7 @@ DEV_DEPENDENCIES = [
     "//rs/artifact_pool",
     "//rs/consensus/mocks",
     "//rs/registry/fake",
+    "//rs/registry/keys",
     "//rs/test_utilities",
     "//rs/test_utilities/registry",
     "//rs/test_utilities/state",

rs/consensus/vetkd/Cargo.toml

@@ -30,6 +30,7 @@ assert_matches = { workspace = true }
 ic-artifact-pool = { path = "../artifact_pool" }
 ic-consensus-mocks = { path = "./mocks" }
 ic-registry-client-fake = { path = "../registry/fake" }
+ic-registry-keys = { path = "../registry/keys" }
 ic-test-utilities = { path = "../test_utilities" }
 ic-test-utilities-registry = { path = "../test_utilities/registry" }
 ic-test-utilities-state = { path = "../test_utilities/state" }