cmd/evm: fix statetest with multi-fork statetest fixtures (#31374)

Fixes `evm statetest` for state test fixtures with multiple fork entries
in their `post` field (e.g.,
[chainId.json](81862e4848/GeneralStateTests/stChainId/chainId.json (L39))).

When these re-activated flags aren't exposed, `statetest` only executes
the fixture for a single fork entry instead of all of the forks as
expected.

This only affects ethereum/tests state test fixtures, not
ethereum/execution-spec-tests (EEST) state tests. EEST writes a separate
fixture/test case (i.e. a separate top-level dict entry in the .json)
for each fork configuration as apposed to combining multiple forks in
one fixture test case: New EEST state tests targeting Prague behavior
are not affected.

cmd/evm/staterunner.go

@@ -53,7 +53,9 @@ var stateTestCommand = &cli.Command{
 	Flags: slices.Concat([]cli.Flag{
 		BenchFlag,
 		DumpFlag,
+		forkFlag,
 		HumanReadableFlag,
+		idxFlag,
 		RunFlag,
 	}, traceFlags),
 }