[llvm] [X86][GlobalISel] Support G_FADD, G_FSUB, G_FMUL, G_FDIV (PR #87339)

[Evgenii Kudriashov via llvm-commits]

e-kud wrote:

@tschuett thanks! I've just copied the existing boilerplate in the file. I'll pay more attention to it while revising other opcodes and I think these ternaries will be extracted similarly to `sMaxScalar`.

https://github.com/llvm/llvm-project/pull/87339