[llvm] [AArch64,ELF] Restrict MOVZ/MOVK to non-PIC large code model (PR #70178)

[Fangrui Song via llvm-commits]

MaskRay wrote:

Rebase (no code change other than formatting).

Reword the description to mention https://github.com/llvm/llvm-project/pull/70262 and clarify that

> This patch adds !getTargetMachine().isPositionIndependent() conditions to clarify that the support is non-PIC only. In addition, add some tests as change detectors in case PIC large code model is supported in the future.

https://github.com/llvm/llvm-project/pull/70178