This reverts commit 22b2f077.

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extra : rebase_source : b3b465b8679fb04ed27193c61bb52c8fb1e6a082

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extra : rebase_source : 31e506acbc041cb597ff14455a7d06b34aca0a70

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extra : rebase_source : 4f0c6c45b777f4f9eeece5f9ca1595753b9a9377

This is necessary to use some C++ APIs, and ugly if not impossible
to work around using cname specifiers and external files.

looks like the declaration analysis phase is too early for building type conversion utility code - do it during type analysis

fix cpp_vector_in_generator test by calling create_from_py_utility_code() early enough to let it inject Cython utility code

use completely separate workspaces for tests to fix cleanup on failures (and to make sharding/parallel test runs straight forward)