[native_assets_builder] Support pub workspaces #1181

Job	Run time
build (ubuntu, stable, native_assets_builder, false)	10m 26s
build (ubuntu, stable, native_assets_cli, false)	2m 57s
build (ubuntu, stable, native_toolchain_c, false)	1m 55s
build (ubuntu, dev, native_assets_builder, false)	6m 19s
build (ubuntu, dev, native_assets_cli, false)	2m 58s
build (ubuntu, dev, native_toolchain_c, false)	1m 53s
build (macos, stable, native_assets_builder, false)	6m 31s
build (macos, stable, native_assets_cli, false)	1m 6s
build (macos, stable, native_toolchain_c, false)	1m 40s
build (macos, dev, native_assets_builder, false)	5m 44s
build (macos, dev, native_assets_cli, false)	1m 54s
build (macos, dev, native_toolchain_c, false)	1m 56s
build (windows, stable, native_assets_builder, false)	8m 54s
build (windows, stable, native_assets_cli, false)	3m 49s
build (windows, stable, native_toolchain_c, false)	5m 55s
build (windows, dev, native_assets_builder, false)	8m 45s
build (windows, dev, native_assets_cli, false)	2m 48s
build (windows, dev, native_toolchain_c, false)	5m 45s
coverage-finished	5s
	1h 21m 20s

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