Use Memory in some more fast methods (#53178)
This commit changes the signature of a bunch of methods that operate on
byte buffers, and which previously didn't take `Memory`. For example, a
method which previously took
```julia
Union{
Array{UInt8},
CodeUnits{UInt8, String},
FastContiguousSubArray{UInt8,N,<:Array{UInt8}} where N,
}
```
Now also takes `Memory{UInt8}`, and the `Memory`-backed
`FastContiguousSubArray`.
## Notes for reviewers
1. I don't think this is a particularly nice design - these large unions
are a sign we miss an abstraction. In particular, whether something is a
contiguous, memory backed Array (read or read/write). I think we should
have a trait for this, which requires an implementation of e.g.
`pointer` and `sizeof`. However, that's a larger PR for another time.
3. The functions `readbytes_some!` and `readbytes_all!` may resize its
arguments. This will not work for `Memory`. It already didn't work for
`SubArray`. Maybe we should have a different method for the arrays that
can't be resized, which doesn't attempt to.
