[CIR] Add Function Argument Demotion support (#170915)

This PR migrates the Function Argument Demotion feature from the
incubator repository to upstream. The feature handles K&R-style function
parameters that are promoted (e.g., short->int, float->double) and
demotes them back to their declared types.

## Changes
- Add emitArgumentDemotion helper function for type demotion
- Create emitFunctionProlog function to handle function prologue setup
(addresses existing TODO to move parameter handling logic)
- Move parameter handling logic into emitFunctionProlog
- Add test case kr-func-promote.c to verify the feature

Tested: All CIR tests pass (320/321, 99.69%). The one unsupported test
is an expected failure.

0 files changed, 0 insertions, 0 deletions