exception_ptr -> exception_wrapper migration

exception_ptr -> exception_wrapper migration

Summary:
integrate exception_wrapper everywhere, and deprecate public methods that take ptrs directly to discourage their use
note that this will break for throwing non-exceptions, which is probably fine

this change opens the door to interesting optimizations for those interested, e.g. Future::then<Exn1, Exn2>(/* func throwing Exn1 and Exn2 */) that autowraps the given types into the resultant future

new benchmark:
```
throwAndCatch                                               23.69us   42.21K
throwAndCatchWrapped                             119.53%    19.82us   50.45K
throwWrappedAndCatchWrapped                      350.16%     6.77us  147.80K
```

Test Plan: existing unit tests, suspected potential perf wins confirmed by benchmark, will wait for windtunnel to see other wins/regressions

Reviewed By: hans@fb.com

Subscribers: search-fbcode-diffs@, apodsiadlo, alikhtarov, andrii, trunkagent, fugalh, njormrod, folly-diffs@, bmatheny

FB internal diff: D1644912

Signature: t1:1644912:1420731849:3dc658dc03bfd6e75d61158808c7dad96092ecfb