gh-149026: Add colour to pickletools CLI output

[hugovk]

Create a pickle file, for example:

import pickle

data = {
    "a": [1, 2.0, 3 + 4j],
    "b": ("character string", b"byte string"),
    "c": {None, True, False},
}

with open("data.pickle", "wb") as f:
    pickle.dump(data, f, protocol=5)

Then ./python.exe -m pickletools data.pickle:

• Issue: Add colour to pickletools CLI output #149026

---

📚 Documentation preview 📚: https://cpython-previews--149027.org.readthedocs.build/

[hugovk]

Aside: the alignment is the same in main without colour, and the code says:

            # make a mild effort to align arguments
            ...
            # make a mild effort to align annotations
            ...

If someone's up for making a bit less mild effort in another PR, go for it!

[picnixz]

Can we have the instruction names in white (no color)? I find it less readable with colors as all instructions have the same color.

[hugovk]

Like this?

Or I think bold cyan is better?

[picnixz]

IMO, too many colors hurt more than they help. White is not that good either actually... I do like the colors for literals and the first column but I feel that colors for instruction names are always too much because it's just adding colors to words that will anyway be classified identically.

Alternatively, how about some "dead" words such as MARK/NONE etc and add categorize the opcodes themselves into colorized categories. This could help a bit more visually (e.g., I want to locate all MARK, whether I use colors or not now I won't be able to find it easily without a CTRL+F).