gh-125420: implement `Sequence.index` API on `memoryview` objects #131491

Job	Run time
Change detection / Compute changed files	11s
Ubuntu SSL tests with OpenSSL (ubuntu-22.04, 3.0.15)	3m 10s
Check if Autoconf files are up to date	30s
Ubuntu SSL tests with OpenSSL (ubuntu-22.04, 3.1.7)	2m 22s
Check if generated files are up to date	3m 44s
Address sanitizer (ubuntu-22.04)	7m 42s
Ubuntu SSL tests with OpenSSL (ubuntu-22.04, 3.2.3)	2m 27s
CIFuzz (address)	18m 33s
Ubuntu SSL tests with OpenSSL (ubuntu-22.04, 3.3.2)	2m 44s
Windows MSI${{ '' }}	0s
CIFuzz (undefined)	20m 54s
Hypothesis tests on Ubuntu	5m 32s
CIFuzz (memory)	20m 33s
Thread sanitizer / Thread sanitizer	4m 25s
Thread sanitizer (free-threading) / Thread sanitizer	7m 32s
WASI / build and test	5m 13s
Ubuntu / build and test (ubuntu-22.04)	7m 15s
Ubuntu (free-threading) / build and test (ubuntu-22.04)	9m 38s
Windows / build (arm64)	3m 9s
Windows (free-threading) / build (arm64)	2m 42s
Windows / build and test (Win32)	15m 33s
Windows (free-threading) / build and test (Win32)	24m 13s
Windows (free-threading) / build and test (x64)	23m 28s
Windows / build and test (x64)	16m 19s
macOS (free-threading) / build and test (ghcr.io/cirruslabs/macos-runner:sonoma)	5m 11s
macOS / build and test (ghcr.io/cirruslabs/macos-runner:sonoma)	4m 19s
macOS / build and test (macos-13)	9m 6s
Docs / Docs	2m 10s
Docs / Docs (Oldest Sphinx)	2m 8s
Docs / Doctest	28m 15s
All required checks pass	1s
	4h 18m 59s

Provide feedback