## Summary of the Pull Request
ControlCore's _renderer (IRenderTarget) is allocated as std::unique_ptr,
but is given to Terminal::CreateFromSettings as a reference.
ControlCore::Close deallocates the _renderer, but if ThrottledFuncs
are still scheduled to call ControlCore::UpdatePatternLocations
it'll cause Terminal::UpdatePatterns to be called, which in turn ends up
accessing the deallocated IRenderTarget reference and lead to a crash.
A proper solution with shared pointers is nontrivial and should be
attempted at a later point in time. This solution moves the teardown of
the _renderer into ControlCore::~ControlCore, where we can be certain
that no further strong references are held by ThrottledFuncs.
## PR Checklist
* [x] Closes#9910
* [x] I work here
* [x] Tests added/passed
## Validation Steps Performed
The crash is a race condition and inherently hard to reproduce.
During validation this PR didn't appear to introduce new crashes.
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