Following #117494, there is now less coupling between compile.c and there are some functions that can move to, and belong better in, flowgraph.c. There include:

- stack effect functions
- _PyCompile_OptimizeCfg
- _PyCfg_FromInstructionSequence

<!-- gh-linked-prs -->
### Linked PRs
* gh-119745
<!-- /gh-linked-prs -->

Move more functions from compile.c to flowgraph.c
This is a GitHub Issue
repo:cpython
owner:python
Title : Move more functions from compile.c to flowgraph.c
Issue date:

--- start body ---
Following #117494, there is now less coupling between compile.c and there are some functions that can move to, and belong better in, flowgraph.c. There include:

- stack effect functions
- _PyCompile_OptimizeCfg
- _PyCfg_FromInstructionSequence

<!-- gh-linked-prs -->
### Linked PRs
* gh-119745
<!-- /gh-linked-prs -->

--- end body ---
