* Move append_vec bench to the crate with append_vec
* Use black_box to tell the compiler not to optimize away test data
```
pub fn black_box<T>(dummy: T) -> T {
unsafe {
let ret = std::ptr::read_volatile(&dummy);
std::mem::forget(dummy);
ret
}
}
```
* Revert "Use black_box to tell the compiler not to optimize away test data"
This reverts commit 5610b8ee95.
* Use black_box to tell the compiler not to optimize away test data
* Create bench directories
* move core tests to core
* remove window
* fix up flaky tests
* test_entryfication needs a singly-threaded banking_stage
* move core benches to core
* remove unnecessary dependencies
* remove core as a member for now, test it like runtime
* stop running tests twice
* remove duplicate runs of tests in perf
* Mostly implement key-value store and add integration points
Essential key-value store functionality is implemented, needs more work to be integrated, tested, and activated.
Behind the `kvstore` feature.
