Rust

strategy: add new `marker_file` strategy #1561

Job	Run time
Tests (release), stable toolchain	1m 54s
Lints, pinned toolchain	38s
Tests (release), minimum supported toolchain	3m 21s
Tests, unstable toolchain (beta)	1m 20s
Tests, stable toolchain	1m 22s
Tests, unstable toolchain (nightly)	2m 57s
	11m 32s

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