define is_nonverlapping function in solana-bpf-loader-program

[kevinheavey]

Problem

This function is currently defined in solana-program-memory but is hidden so as not to be part of the API. It brings along a num-traits dep. The version of it that is used in solana-program-memory does not need num-traits. Since it is a very small function, I think it's fine to have two similar definitions of it, both of which are private

Summary of Changes

Define it in solana-bpf-loader-program. I am making a separate PR to solana-sdk to remove num-traits from that one

[mergify]

The Firedancer team maintains a line-for-line reimplementation of the
native programs, and until native programs are moved to BPF, those
implementations must exactly match their Agave counterparts.
If this PR represents a change to a native program implementation (not
tests), please include a reviewer from the Firedancer team. And please
keep refactors to a minimum.