On CPU always use `NoDynamicCheck()`, just finish the last partial workgroup with `DynamicCheck()`

Given that `DynamicCheck()` breaks SIMD this can be an order of magnitude faster for some inexpensive tasks.

I'll write up a better MWE, but this is the scale of it - a single threaded game of life in DynamicGrids.jl (basically summing a 3x3 window over Bool) is 2x faster than an 8 core KernelAbstractions.jl sim pretty much just from `DynamicCheck()`:
```julia
julia> using DynamicGrids, BenchmarkTools

julia> init = rand(Bool, 1000, 1000);

julia> output = ResultOutput(init; tspan=1:200);

julia> @btime sim!($output, Life(); proc=SingleCPU());
338.058 ms (6459 allocations: 3.25 MiB)

julia> @btime sim!($output, Life(); proc=CPUGPU());
652.198 ms (18401 allocations: 4.63 MiB)
```

Start by reproducing the provided DynamicGrids.jl benchmark and comparing CPU execution with and without DynamicCheck(). Trace the CPU path involving NoDynamicCheck() and DynamicCheck(); done means the final partial workgroup still uses DynamicCheck() while ordinary CPU work avoids it without changing results.

Written by the indexing model from the issue text.