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.
When the SelfMetadata in a witness thunk is the tuple type (repeat each Self),
we can fulfill the pack shape and type metadata for Pack{repeat each Self}
from tuple metadata.
The length is trivially projected; the type metadata pack is slightly more
involved, because tuple metadata stores a list of element/offset pairs, so
we must stack allocate a pack and fill it in.
