[test] Mark tests that use experimental/upcoming features as such

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.

test/ModuleInterface/stored-properties.swift

@@ -14,6 +14,8 @@
 // RUN: %target-swift-frontend -enable-experimental-feature StructLetDestructuring -emit-module -o %t/TestResilient.swiftmodule -module-name StoredProperties -enable-library-evolution %t-resilient.swiftinterface -disable-objc-attr-requires-foundation-module
 // RUN: %target-swift-frontend -enable-experimental-feature StructLetDestructuring -emit-module -o /dev/null -merge-modules %t/TestResilient.swiftmodule -module-name StoredProperties -enable-library-evolution -emit-module-interface-path - | %FileCheck %s --check-prefix RESILIENT --check-prefix COMMON
 
+// REQUIRES: swift_feature_StructLetDestructuring
+
 // COMMON: public struct HasStoredProperties {
 public struct HasStoredProperties {
   // COMMON: public var computedGetter: Swift.Int {