Add `Base.format_bytes(; binary=false)` option (#50572)
Add a `binary` keyword argument to `Base.format_bytes` that enables
switching between the default units KiB, MiB, GiB, etc. and kB, MB, GB.
I've wanted this feature multiple times before so I thought I should
just make a PR.
```julia
julia> Base.format_bytes(12345678)
"11.774 MiB"
julia> Base.format_bytes(12345678; binary=false) # with this PR
"12.346 MB"
```
