refactor: inline virtual_impl #29687

Job	Run time
Format	1m 3s
Build (macos-latest, 5.1.x)	13m 22s
Build (ubuntu-latest, 5.1.x)	8m 25s
Documentation	57s
Nix (macos-latest)	1m 52s
Wasm_of_ocaml	10m 13s
Build (ocaml-variants.5.4.0+trunk, ubuntu-latest, true)	1m 33s
Nix (ubuntu-latest)	50s
Build (4.14.x, ubuntu-latest, true)	1m 26s
Build (4.14.x, macos-latest, true)	2m 11s
Build microbenchmarks	2m 32s
Coq 8.16.1	7m 5s
Create local opam switch (macos-latest, 5)	7m 15s
Build (5.1.x, macos-13, true)	3m 40s
Create local opam switch (macos-latest, 4.14)	5m 57s
Build (ocaml-base-compiler.4.14.2,system-msvc, windows-latest)	14m 10s
Create local opam switch (ubuntu-latest, 5)	4m 47s
Build monorepo benchmark docker image	3m 39s
Build (ocaml-base-compiler.5.1.1,system-mingw, windows-latest)	8m 8s
Create local opam switch (ubuntu-latest, 4.14)	4m 45s
Build (4.08.x, ubuntu-latest, true)	1m 27s
Build (4.04.x, ubuntu-latest, true, true)	4m 22s
Build (4.02.x, ubuntu-latest, true)	4m 2s
	1h 53m 41s

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