[llvm] [JITlink][AArch32] Move function declaration from unittest to headers (PR #71621)

[Stefan Gränitz via llvm-commits]

weliveindetail wrote:

Hi Tom, these encoding functions are implementation details and weren't supposed to clutter the API. The idea was to only expose them for unit testing. Is there a policy or a technical reason that requires this change?

https://github.com/llvm/llvm-project/pull/71621