[mem] Exposition-only style for private members

Affected sections:
- [out.ptr.t]
  - Changes `s`, `a`, and `p`.
- [inout.ptr.t]
  - Changes `s`, `a`, and `p`.
- [mem.res.class]
  - Changes `max_align`, renaming it to `max-align`.
- [mem.poly.allocator.class]
  - Changes `memory_rsrc`, renaming it to `memory-rsrc`.
- [mem.res.monotonic.buffer]
  - Changes `upstream_rsrc`, `current_buffer`, and `next_buffer_size`,
renaming them to `upstream-rsrc`, `current-buffer`, and
`next-buffer-size` respectively.
- [allocator.adaptor]
  - Changes `OuterTraits`, renaming it to `outer-traits`.

Author: frederick-vs-ja