[llvm] [RISCV][GISEL] Legalize G_INSERT_SUBVECTOR and G_EXTRACT_SUBVECTOR for scalable vectors (PR #108220)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

Title is wrong, this is not handling G_INSERT_SUBVECTOR or G_EXTRACT_SUBVECTOR. This only handles G_INSERT / G_EXTRACT

https://github.com/llvm/llvm-project/pull/108220