[llvm] [CodeGen][ARM64EC] Factor out emitFunctionAlias and getSymbolFromMetadata in emitFunctionEntryLabel. (PR #92098)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

As this seems to be a pure refactoring with no test changes, I'd suggest adding NFC somewhere in the commit/PR subject line.

https://github.com/llvm/llvm-project/pull/92098