Instead of some functions operating with hex strings,
and others using bytes, this consolidates most things to use bytes.
This mainly focuses on bitcoin.py and transaction.py,
and then adapts the API usages in other files.
Notably,
- scripts,
- pubkeys,
- signatures
should be bytes in almost all places now.
```
$ python3 -O
Python 3.10.6 (main, Mar 10 2023, 10:55:28) [GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> assert (x := 2)
>>> x
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'x' is not defined
```
pity. it looked to be a neat and concise pattern.
Required a much higher mental load to parse the name "convert_bip32_path_to_list_of_uint32"
than to parse "convert_bip32_strpath_to_intpath".
And we already have the ~inverse: "convert_bip32_intpath_to_strpath".
