Find all the usages of `--enable-experimental-feature` or
`--enable-upcoming-feature` in the tests and replace some of the
`REQUIRES: asserts` to use `REQUIRES: swift-feature-Foo` instead, which
should correctly apply to depending on the asserts/noasserts mode of the
toolchain for each feature.
Remove some comments that talked about enabling asserts since they don't
apply anymore (but I might had miss some).
All this was done with an automated script, so some formatting weirdness
might happen, but I hope I fixed most of those.
There might be some tests that were `REQUIRES: asserts` that might run
in `noasserts` toolchains now. This will normally be because their
feature went from experimental to upcoming/base and the tests were not
updated.
This makes ManagedBuffer available and usable in Embedded Swift, by:
- Removing an internal consistency check from ManagedBuffer that relies on metatypes.
- Making the .create() API transparent (to hoist the metatype to the callee).
- Adding a AllocRefDynamicInst simplification to convert `alloc_ref_dynamic` to `alloc_ref`, which removes a metatype use.
- Adding tests for the above.
