gh-102511: Add C implementation of `os.path.splitroot()` #110113

Job	Run time
Check for source changes	12s
Check if generated files are up to date	4m 54s
Address sanitizer	9m 25s
Ubuntu SSL tests with OpenSSL (1.1.1w)	2m 4s
CIFuzz (address)	19m 50s
Ubuntu SSL tests with OpenSSL (3.0.13)	1m 58s
Hypothesis tests on Ubuntu	5m 39s
CIFuzz (undefined)	21m 12s
Ubuntu SSL tests with OpenSSL (3.1.5)	1m 57s
CIFuzz (memory)	22m 13s
Ubuntu SSL tests with OpenSSL (3.2.1)	2m 14s
Windows (free-threading) / build and test (x64)	27m 28s
Windows (free-threading) / build (arm64)	2m 34s
Windows (free-threading) / build and test (x86)	29m 40s
macOS / build and test (macos-14)	7m 42s
macOS / build and test (macos-13)	9m 23s
macOS (free-threading) / build and test (macos-14)	9m 50s
Ubuntu / build and test	7m 27s
Ubuntu (free-threading) / build and test	9m 43s
Thread sanitizer / Thread sanitizer	4m 12s
Thread sanitizer (free-threading) / Thread sanitizer	6m 13s
WASI / build and test	11m 38s
Windows / build and test (x64)	15m 55s
Windows / build (arm64)	3m 0s
Windows / build and test (x86)	15m 2s
Docs / Docs	1m 59s
Docs / Docs (Oldest Sphinx)	1m 34s
Docs / Doctest	13m 55s
All required checks pass	1s
	4h 28m 54s

Provide feedback