Android DetailedList: use theme text colors (replace R.color.black)

[rasmusJenle]

Problem
On Android, DetailedList currently hard-codes R.color.black for row text.
In dark mode, this makes text unreadable (black text on dark background).
Fixes #3747.

Solution
Replace the hard-coded color with theme-resolved colors:
top_text: resolved from android.R.attr.textColorPrimary
bottom_text: resolved from android.R.attr.textColorSecondary
Fallback: Color.BLACK

Screenshots with solution implemented

As pointed out by freakboy3742 when the issue was raised, the decision whether to use textColorPrimary or textColorSecondary for bottom_text requires attention to android best practice. After looking at https://m3.material.io/components/lists/specs, I landed on textColorSecondary. top_text and bottom_text seem to work like a headline and supporting text, with varying emphases on color/contrast.

[johnzhou721]

Some unofficial suggestions. If you disagree with any of those or can't work them out, feel free to wait for a core team member.

[rasmusJenle]

CI note

The Android testbed is currently failing during Gradle dependency resolution with repeated
HTTP 403 Forbidden responses from https://repo.maven.apache.org/maven2/ (protobuf, gson, grpc, etc.).
Windows testbed was green on the initial run; subsequent failures there appear flaky
(timing / environment related) and likely unrelated to this change, which is Android-specific.
I’ve retriggered CI to rule out transient issues.

[freakboy3742]

The CI issues were transient; GitHub apparently has a surprisingly difficult time maintaining connections to the internet. I've re-run CI, and it has all passed; but there is still a documentation build issue that I think will be resolved if you merge with main.

[mhsmith]

Thanks for fixing this!