Return bundle metadata from bundle building. #3122

Job	Run time
Book tests	14s
Bitrot check	2m 46s
Latest build on ubuntu-latest	53s
Build target wasm32-wasi	2m 12s
Latest build on windows-latest	2m 4s
Intra-doc links	2m 53s
Latest build on macOS-latest	4m 3s
Code coverage	9m 5s
Rustfmt	10s
Test on ubuntu-latest	8m 44s
Test on windows-latest	9m 23s
Test on macOS-latest	8m 17s
	50m 44s

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