Add template deduction guide for Slice constructor #5744

Job	Run time
Clippy	0s
Clang Tidy	0s
ESLint	0s
Bazel on ${{ (((matrix.os == 'ubuntu') && 'Linux') \|\| ((matrix.os == 'macos') && 'macOS') \|\| ((matrix.os == 'windows') && 'Windows') \|\| '???') }}	0s
Outdated	0s
Reindeer	0s
pre_ci / pre_ci	2s
Minimal versions	22s
Documentation	25s
Rust nightly	58s
Rust beta	51s
Rust stable	55s
Rust 1.82.0	53s
Rust 1.77.0	53s
Rust 1.74.0	29s
Rust 1.73.0	29s
Cargo on macOS	48s
Cargo on Windows (msvc)	2m 2s
C++14	56s
C++17	1m 4s
C++20	59s
	12m 6s

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