Add the newly mapped symbols to SymbolPlayground

[Ceylo]

This PR adds eight rows to SymbolPlayground: bubble, message, safari, exclamationmark.bubble, square.and.arrow.down and ellipsis.bubble (skiptools/skip-ui#525, merged), then rectangle.grid.2x2 and slider.horizontal.3 (skiptools/skip-ui#548, draft). Each sits where its Material icon falls in skip-ui's mapping order, as the existing rows do.

Until a skip-ui release includes both, the rows show the warning triangle on Android.

iOS 26.5	Android, before	Android, after

The two rows from skiptools/skip-ui#548:

iOS 26.5	Android, before	Android, after

Parent PRs:

• Map six more SF Symbols to Material icons skip-ui#525
• Map rectangle.grid.2x2 and slider.horizontal.3 to Material icons skip-ui#548

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Skip Pull Request Checklist:

• REQUIRED: I have signed the Contributor Agreement
• REQUIRED: I have tested my change locally with swift test. This package has no test targets. Instead, the app was built through Gradle in Lite and Fuse.
• OPTIONAL: I have tested my change on an iOS simulator or device
• OPTIONAL: I have tested my change on an Android emulator or device

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• AI was used to generate or assist with generating this PR. Please specify below how you used AI to help you, and what steps you have taken to manually verify the changes.

Written with Claude Code, together with the skip-ui mapping. Every claim above comes from a run: the playground on an API 37 emulator (Lite and Fuse) before and after the skip-ui change, and on an iPhone 17 simulator (iOS 26.5).