Handle absolute paths in typegen #5073

Job	Run time
build-rewatch (macos-13, x86_64-apple-darwin)	18s
build-rewatch (macos-14, aarch64-apple-darwin)	16s
build-compiler (ubuntu-latest, ocaml-variants.5.2.0+options,ocaml-option-static, true, true, true...	1m 8s
build-rewatch (ubuntu-latest, x86_64-unknown-linux-musl)	13s
build-compiler (buildjet-2vcpu-ubuntu-2204-arm, ocaml-variants.5.2.0+options,ocaml-option-static,...	2m 19s
build-compiler (macos-13, 5.2.0, true)	2m 59s
build-rewatch (buildjet-2vcpu-ubuntu-2204-arm, aarch64-unknown-linux-musl)	17s
build-compiler (macos-14, 5.2.0, true)	1m 40s
build-rewatch (windows-latest, x86_64-pc-windows-gnu)	21s
build-compiler (windows-latest, 5.2.0, true)	2m 48s
build-compiler (ubuntu-latest, ocaml-variants.5.0.0+options,ocaml-option-static)	1m 9s
build-compiler (ubuntu-latest, ocaml-variants.4.14.2+options,ocaml-option-static)	1m 8s
build-compiler (ubuntu-latest, ocaml-variants.4.13.0+options,ocaml-option-static)	1m 19s
package	0s
installationTest	0s
publish	0s
	15m 55s

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