Adds shadowColor property to the Card widget

[josh-burton]

Description

Adds a new shadowColor property to the Card widget, to allow customizing the shadow color.

Related Issues

#47272
#33257

Tests

I added the following tests:

card_test.dart - added a test that ensures the cards default shadow color is black, and that if a shadowColor is set, the Material shadowColor gets that value.

card_theme_test.dart - modified tests to check that the material gets the shadow color from the card theme.

Checklist

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• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I signed the [CLA].
• I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I updated/added relevant documentation (doc comments with ///).
• All existing and new tests are passing.
• The analyzer (flutter analyze --flutter-repo) does not report any problems on my PR.
• I am willing to follow-up on review comments in a timely manner.

Breaking Change

Did any tests fail when you ran them? Please read [Handling breaking changes].

• No, no existing tests failed, so this is not a breaking change.

[justinmc]

Thanks for the PR! I think this makes sense. Just one small comment about code order in the test.

@HansMuller Is this alright given the proposed changes to theming?

[josh-burton]

@HansMuller @justinmc is there any other changes needed on this?

[justinmc]

LGTM

Thanks for the contribution and sorry I didn't notice you had updated it! There was one test failure, but it looked like an unrelated timeout to me. I'll rerun that and try to get this merged.

[fluttergithubbot]

This pull request is not suitable for automatic merging in its current state.

• The status or check suite web_tests-2-linux has failed. Please fix the issues identified (or deflake) before re-applying this label.

[josh-burton]

Thanks @justinmc!