[RISCV] Precommit jump table test for chipsalliance-veer-eh1. NFC (#241434)
Add a test of jump-table lowering for dense 9-case and 10-case switches
on chipsalliance-veer-eh1 and generic-rv32. A follow-up change raises
the minimum jump-table size for this CPU, and this test will show the
resulting codegen difference.
Assisted-by: Claude