Remove rich as required for tree()

[ianhi]

Description

I often found that when I wanted to use tree() rich wasn't installed. So I started out with this as a fallback but on looking into it I think it can be fully removed in favor a small loop (which we would need anyway for a fallback) to construct the tree and just add in ansi or html bolding codes.

One thing I noticed when looking at this is that there is currently no truncation for extremely large hierarchies. I think that is bad for two reasons:

1. can massively overflow the users screen
2. Potentially bad performance doing the IO to get the full hierarchy.

So I've added a simplistic truncation. Note that this can result in nodes that are displayed having missing children.

I also added a plain flag to give the user explicit control on the bolding html/ansi sequences.

Output

Per the tests the output is equivalent, and also looks so to my eyes.

To compare here is a script (runnable with third-wheel)

uvx third-wheel@0.3.0 run compare_trees.py

compare_trees.py

# /// script
# dependencies = [
#   "zarr_old",
#   "rich",
#   "zarr @ git+https://github.com/ianhi/zarr-python@ian/simple-tree",
# ]
# [tool.third-wheel]
# renames = [
#   {original = "zarr", new-name = "zarr_old", extras = ["optional"]},
# ]
# ///

"""Compare the old rich-based tree with the new plain tree."""

import zarr
import zarr_old

def make_group(mod):
    g = mod.group()
    g.create_group("A")
    g.create_group("B")
    g.create_group("B/C")
    g.create_group("B/C/D")
    return g

print("=== Old (rich-based) tree ===")
g_old = make_group(zarr_old)
print(repr(g_old.tree()))

print("=== New tree (styled) ===")
g_new = make_group(zarr)
print(repr(g_new.tree()))

print("=== New tree (plain) ===")
print(repr(g_new.tree(plain=True)))

or in jupyter:

TODO:

• Add unit tests and/or doctests in docstrings
• Add docstrings and API docs for any new/modified user-facing classes and functions
• New/modified features documented in docs/user-guide/*.md
• Changes documented as a new file in changes/
• GitHub Actions have all passed
• Test coverage is 100% (Codecov passes)