Restart EditableText cursor timer when it moves

[tgucio]

Description

Reset the cursor timer in _handleSelectionChanged() so as to keep it from blinking when it's moved using keyboard.

Related Issues

#69321

Behaviour before and after the change

Before:

After:

Tests

I added the following tests:

packages/flutter/test/widgets/editable_text_cursor_test.dart:
testWidgets('Cursor animation restarts when it is moved using keys on desktop', (WidgetTester tester)

Relevant tests passing:

% flutter test test/widgets/editable_text_cursor_test.dart
00:15 +24: All tests passed!
% flutter test test/widgets/editable_text_show_on_screen_test.dart
00:05 +9: All tests passed!
% flutter test test/widgets/editable_text_test.dart
00:12 +152: All tests passed!

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• 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.
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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.
• Yes, this is a breaking change. If not, delete the remainder of this section.
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[goderbauer]

(PR triage): Looks like the analyzer is unhappy. Can you take a look and fix that?

[tgucio]

(PR triage): Looks like the analyzer is unhappy. Can you take a look and fix that?

My bad. I ran the analyzer with another flutter checkout on PATH. Running as "bin/flutter analyze --flutter-repo" helped.

Anyway, the issue was with 2 warnings in the test - I pushed an amended commit and tests are under way.

[justinmc]

LGTM, thanks for fixing this!

This will also reset the timer on mobile and when clicking/tapping instead of using keys, but I think that is desired behavior as well.

I confirmed that the test will fail without the fix.

[justinmc]

FYI @LongCatIsLooong.

I was just reading your RenderEditable painters design doc and thought this was somewhat related, just giving you a heads up.