Add val_fmt_image() to enable image rendering in various components

[jrycw]

Related to #418.

It seems that users are interested in rendering images across different components. To support this, I'd like to propose introducing a val_fmt_image() function. With this function, we can achieve more flexibility, such as:

import polars as pl
from polars import selectors as cs
from great_tables import GT, vals, html
from importlib_resources import files


img_paths = files("great_tables") / "data/metro_images"

df = pl.DataFrame(
    {
        "col1": list("123"),
        "col2": list("123"),
        "col3": list("123"),
        "group": ["grp_a", "grp_a", "grp_b"],
        "row": ["row_1", "row_2", "row_3"],
    }
)

img1, img2, img3, img4, img5, img6 = vals.fmt_image(
    list("123456"), path=img_paths, file_pattern="metro_{}.svg"
)

(
    GT(df)
    .cols_label(**{"col1": html(img1), "col2": html(img2), "col3": html(img3)})
    .tab_stub(groupname_col="group", rowname_col="row")
    .tab_stubhead(html(img4))
    .tab_header(title=html(img5))
    .tab_source_note(html(img6))
    .fmt_image(cs.starts_with("col"), path=img_paths, file_pattern="metro_{}.svg")
)

The idea is to wrap the output from val_fmt_image() in the html() function.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.84%. Comparing base (c8a7ff8) to head (60d81b8).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #451      +/-   ##
==========================================
+ Coverage   87.70%   87.84%   +0.13%     
==========================================
  Files          42       42              
  Lines        4832     4838       +6     
==========================================
+ Hits         4238     4250      +12     
+ Misses        594      588       -6     

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[rich-iannone]

This will be a great addition, thank you! If you can, could you add some basic tests for this function in a new test_formats_vals.py file? I know we aren't directly testing the other val_fmt_* functions right now but this will get the process started.

[jrycw]

Sure. Since we have actual SVG files in the project, I thought it might be a good idea to directly test val_fmt_image() using those images. Feel free to update the tests if they need further refinement.

[Yasin197]

This would be an amazing feature, when do you think it will be released?

[rich-iannone]

LGTM!

[rich-iannone]

Sorry for taking awhile to get back to this PR. Just reviewed again, did some testing, and everything is really good here!