TRACKER: Related pandas-dev/pandas master PRs for Generalized Window Operations

[mroeschke]

Pull requests:

• Splitting pandas/core/window.py into a directory: REF: pandas/core/window.py into multiple files pandas-dev/pandas#27736
• Typing in pandas/core/window.py: TYPING: pandas/core/window.py pandas-dev/pandas#27391
• Splitting window tests: CLN: Split test_window.py pandas-dev/pandas#27305
• Peak memory benchmarks for rolling: BENCH: Add peakmem benchmarks for rolling pandas-dev/pandas#28255
• Refactor window aggregations from window indexers: REF: Separate window bounds calculation from aggregation functions pandas-dev/pandas#29428
• Create a new directory, pandas/_libs/window/: REF: Create _lib/window directory pandas-dev/pandas#29817