Refactor generate_ci_workflows (#61879)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61879
Refactor generate_ci_workflows to support CI dispatcher. This is the first step to refactor the workflow into a dataclass with some validation and OOP.
Verified that the output is the same:
```
.github/scripts/generate_ci_workflows.py
git status
```
Test Plan: Imported from OSS
Reviewed By: seemethere
Differential Revision: D29808365
Pulled By: zhouzhuojie
fbshipit-source-id: b8c5fd43f4bd6e17e06f3925a1a509084b790d95
