[llvm] [RISCV][GISel] Legalize G_INSERT_VECTOR_ELT for supported vector types (PR #159708)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

Can you add end to end IR tests? Those should be the preferred starting point for all legalizer tests. Mir should be left for testing edge cases 

https://github.com/llvm/llvm-project/pull/159708