limit lines in html repr of dataset attrs

[Ostheer]

Truncates the amount of lines output by _html_repr_ for DataSet/DataArray objects.

Motivation is that currently, if an attribute has a larger number of line breaks, it will pollute your Jupyter (etc) view.
For example, I like to append the measurement script source file to all my measurement results. When I then load the netcdf file, the attributes will contain a file with potentially hundreds of lines. I don't want all these lines to be shown in my output cells when viewing the html representation.

In the suggested edit, max_lines defines above which amount of lines the output should be truncated, while min_lines defines how many should still be shown (like a preview). The current values of 15 and 10 are somewhat arbitrary.

[Ostheer]

Uh, the macos-latest py3.11 test was cancelled after a few hours (it was 95% done):

The job running on runner GitHub Actions 6 has exceeded the maximum execution time of 360 minutes.

[dcherian]

Since this is the HTML repr, it'd be nice to allow the user to "click to expand" long entries. Do you know how to do that? (ping @benbovy )

I think a corresponding change to truncate the text repr would be fine.

[Ostheer]

I may be able to implement that, hopefully some time in the upcoming days.

[benbovy]

For the html repr an option that is easy to implement would be to add max-height and overflow-y: scroll CSS properties here:

xarray/xarray/static/css/style.css

Lines 256 to 261 in 1e361cc

	.xr-attrs dt {
	white-space: nowrap;
	overflow: hidden;
	text-overflow: ellipsis;
	padding-right: 10px;
	}

I don't think the default browser scrollbar will look very pretty inside the repr, but it might be OK if we don't set max-height to a too small value.

A "click to expand" UI would certainly look prettier, but I doubt it would be easy to implement that in pure-CSS. "Expand on hover" is easier but that would be quite annoying UX I think.