Optimizations for VRDirectCB #483

VRDirectCB needs some code optimizations. Clear things to do:

• Create a separate FunctionWrapper mode, i.e. VRDirectCBFW which wraps things in FunctionWrappers for cases with large numbers of jumps
• Check https://github.com/SciML/JumpProcesses.jl/pull/477/files#diff-ef724e728ebe5838ea90cbda75a1e828afc91def61764cfec717b4ba24b7580bR174-R177 constant props
• Create flamegraphs to showcase other potential performance bottlenecks
• Setup a benchmark in SciMLBenchmarks (i.e. finish Benchmarking Variable Rate Aggregator SciMLBenchmarks.jl#1230)
• Change VRDirectCB to the default when demonstrated as more efficient.
• Make sure everything is type stable with regards to the VRJs and rate/affect evaluation in the no FunctionWrapper case.
• Reuse last cur_rates evaluation from the condition in the affect if it is at the correct time (i.e. if the quadrature uses the endpoints).
• See if additional @inbounds decorators improves performance
• use preallocated u_tau instead of out-of-place evaluation.
• Think about what order / type of quad rule to use. Why are we using the 4-point Gauss-Legendre quadrature currently? (For example, we could use a rule that includes endpoints to avoid recalculating the cumulative rate sum at the final point.)