Introduce PPC_IMPLEMENTATIONS variable #3803

Job	Run time
pre-commit / pre-commit	1m 13s
ubuntu / gcc-build (ubuntu-24.04-arm, Release)	1m 9s
ubuntu / gcc-build (ubuntu-24.04, Debug)	58s
ubuntu / gcc-build (ubuntu-24.04, Release)	1m 10s
ubuntu / gcc-build (ubuntu-24.04-arm, Debug)	1m 14s
mac / clang-build (Release)	1m 52s
ubuntu / clang-build (ubuntu-24.04-arm)	55s
mac / clang-build (Debug)	2m 33s
ubuntu / clang-build (ubuntu-24.04)	47s
windows / msvc-build (Debug)	2m 41s
windows / clang-build	2m 55s
windows / msvc-build (Release)	2m 1s
mac / clang-test	4m 49s
ubuntu / clang-sanitizer-build (ubuntu-24.04)	56s
ubuntu / clang-test (ubuntu-24.04)	8m 21s
ubuntu / clang-test (ubuntu-24.04-arm)	8m 21s
mac / clang-test-extended	3m 15s
windows / clang-test	3m 40s
windows / msvc-test	7m 3s
ubuntu / clang-sanitizer-test (ubuntu-24.04)	2m 57s
ubuntu / gcc-test (ubuntu-24.04-arm)	8m 30s
ubuntu / gcc-test (ubuntu-24.04)	8m 21s
windows / clang-test-extended	3m 5s
windows / msvc-test-extended	3m 2s
ubuntu / clang-sanitizer-test-extended (ubuntu-24.04)	2m 26s
ubuntu / clang-test-extended (ubuntu-24.04)	4m 32s
ubuntu / clang-test-extended (ubuntu-24.04-arm)	4m 45s
ubuntu / gcc-test-extended (ubuntu-24.04)	4m 32s
ubuntu / gcc-test-extended (ubuntu-24.04-arm)	4m 38s
ubuntu / gcc-build-codecov	5m 58s
perf / macos-clang-build-perf-stats	2m 40s
perf / ubuntu-gcc-build-perf-stats	1m 29s
pages / build-scoreboard	18s
pages / build-doxygen-xml	1m 28s
pages / build-sphinx	39s
pages / deploy-pages	0s
	1h 55m 13s

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