This can be used to erase all allocations made within the named memory
pool. The usual use case would be for arena allocators, which allocate
by advancing a pointer and never have to free the memory. There is no
tracking of individual allocations and everything is freed frequently,
by reseting the pointer, for example once per frame.
Since this is used in special-purpose allocators, there is no support
for discarding the memory of the default memory pool.
When using TRACY_MANUAL_LIFETIME, calling most Tracy functions
before starting the profiler results in an assertion. Notably, even
TracyIsConnected is affected. There is, however, no function to check if
the profiler had already started. This commit adds such a function.
