GeezerVison

1. add `tp_new` to guarantee `ob_bytes_head` is always set, often to the empty
   bytes singleton.
2. `ob_alloc` information is now redundant, added assertion to validate that,
   would it make sense to deprecate?
3. There's a lot of `bytearray` code very similar to `bytes` code, more could
   likely be just proxied to the `bytes` now. Here just focusing on the swap as
   that enables optimizations.
4. If `bytearray` is passed a single-reference bytes it could potentially take
   "ownership" of it without copying the bytes, for now not implemented.

This enables adding `bytearray._detach()` which I plan to do in a separate PR.

```bash
 # `_io` large file read test
./python -m test -M8g -uall test_largefile -m test.test_largefile.CLargeFileTest.test_large_read

 # `_pyio` large file read test
./python -m test -M8g -uall test_largefile -m test.test_largefile.PyLargeFileTest.test_large_read
```

On my machine (AMD 64 bit Linux, Optimized build):
`_io` takes: ~0.791s and uses ~2GB of RAM
`_pyio` current: ~1.073s and uses ~4GB of RAM
`_pyio` w/ bytearray._detach: ~0.887s and uses ~2GB of RAM

Perf checking no major swings in an optimized build:
`./python -E -bb -Wd -m test -uall -M32G test_bytes test_capi.test_bytearray -vvv`

before: ~1.4s
after: ~1.5s

Previous discussion: https://discuss.python.org/t/add-zero-copy-conversion-of-bytearray-to-bytes-by-providing-bytes/79164