Improve Download with Index and Filename parameters

[hoxbro]

This PR does two things:

• Add the ability to save or not to save the Index
  • Was possible before with kwargs={'index': False}.
  • I have kept it as True to follow the default used by pandas to_xxx methods.
• Add Filename
  • If this is not defined, it will try self.view.title and thereafter self.view.pipeline.table and clean either of them up to be a valid filename. I have chosen not to do this with the parameter, as a user will expect the actually input to be the filename.

Code used for the filename:

import numpy as np
import pandas as pd
import panel as pn
from lumen.pipeline import Pipeline
from lumen.sources import FileSource
from lumen.views import Table
from lumen.views.base import Download

pn.extension("tabulator")

np.random.seed(1)
df = pd.DataFrame({"revenue": np.random.uniform(0, 10000, 30)})
df.to_parquet("data.parq")

source = FileSource(files=["data.parq"])
pipeline = Pipeline(source=source, table="data", name="Pipeline")

table = Table(
    pipeline=pipeline,
    download=Download(format="csv", index=False, filename="test"),
    # download=Download(format="csv", index=False),
    title="This is my ??test!!!!",
)
table

[codecov-commenter]

Codecov Report

Merging #438 (369ae81) into main (5475c1a) will increase coverage by 0.07%.
The diff coverage is 82.05%.

@@            Coverage Diff             @@
##             main     #438      +/-   ##
==========================================
+ Coverage   69.25%   69.32%   +0.07%     
==========================================
  Files          76       76              
  Lines        8883     8914      +31     
==========================================
+ Hits         6152     6180      +28     
- Misses       2731     2734       +3     

Impacted Files	Coverage Δ
lumen/views/base.py	64.88% <60.00%> (+0.07%)	⬆️
lumen/util.py	68.39% <87.50%> (+0.74%)	⬆️
lumen/tests/views/test_base.py	100.00% <100.00%> (ø)

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[philippjfr]

Looks good, thank you!

[github-actions]

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