Move the management of Jsoo config details out of dune (#13613) #38084

Job	Run time
Build with OxCaml (ubuntu-latest)	26m 23s
Cygwin Build	2m 59s
Documentation	58s
Test that the utop dev tool can be built and run	9m 15s
Bootstrap (ubuntu-latest)	4m 37s
Nix Build 4.08 (ubuntu-latest)	6m 4s
Nix Build (ubuntu-latest)	1m 14s
Nix Build (macos-latest)	3m 22s
Format	1m 29s
Nix Tests (ubuntu-latest)	8m 26s
Build microbenchmarks	2m 3s
Rocq 9.1	7m 44s
Rocq 9.1 (native)	13m 47s
Building Dune with OxCaml	32m 51s
Wasm_of_ocaml	8m 8s
Create local opam switch (ubuntu-latest, 5)	4m 54s
Create local opam switch (macos-latest, 5)	10m 1s
Build (5.4.x, 5.4.x, macos-latest, true)	12m 0s
Build (ocaml-compiler.5.4.0,system-msvc, windows-latest, ocaml-compiler.5.4.0-system-msvc, true)	18m 8s
Build (ocaml-variants.5.5.0+trunk, ocaml-variants.5.5.0+trunk, ubuntu-latest)	5m 43s
Build (ocaml-base-compiler.5.4.0,system-mingw, windows-latest, ocaml-compiler.5.4.0-system-mingw,...	21m 31s
Build (5.4.x, 5.4.x, macos-15-intel)	4m 27s
Build (5.4.x, 5.4.x, ubuntu-latest, true)	9m 53s
Build (ocaml-variants.4.14.2+options,ocaml-option-32bit, ocaml-variants.4.14.2-ocaml-option-32bit...	4m 12s
Build (4.14.x, 4.14.x, ubuntu-latest)	1m 36s
Build (4.14.x, 4.14.x, macos-latest)	7m 7s
	3h 48m 52s

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