Implement support for multiple commands in one native executable

[fschutt]

Fixes #3425.
Fixes #3374.
Fixes #3436.

TODO

Currently we aren't running integration tests on Windows, so this led to problems when debugging, since

I can only re-enable integration tests after #3353 is merged, since that PR will change the CI structure massively (doesn't make sense to re-enable before).

I temporarily enabled linking towasmer-headless.a and got the binary size of the exe from 24 MB to 9 MB stripped, but this is causing issues on linux-aarch64 because we currently build libwasmer-headless.a with the wrong flags.

• Refactor create-obj and create-exe
• Fix create-exe to use caching with --precompiled-atom syntax
• Fix --precompiled-atom caching not working with linker (esp. --object-format serialized is causing linker issues)
• Re-enable integration tests on Windows after Speed up CI #3353 is merged

[fschutt]

Okay @syrusakbary it seems that the object files generated by Artifact::generate_object are corrupted both on master and on multi-command-exe. I’ll hand this issue over to @ptitSeb since he has more context on this.