fix: improve sidebar UI

[LucasXu0]

Feature Preview

• revert dark main color
• change workspace name font size to 15.0
• only show collapse button when hovering the sidebar
• remove expand button after workspace name
• change settings icon opacity to 0.7
• replace favorite header icon
• add arrow icon after section name
• replace trash bin icon
• adjust collapse icon padding
• redesign question bubble
• add view button padding
• section header icon size
• replace default page icon
• add hover effect to add view button
• add hover effect to arrow icon
• add more padding to tooltip
• remove trash button padding
• replace favorite icon

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PR Checklist

• My code adheres to AppFlowy's Conventions
• I've listed at least one issue that this PR fixes in the description above.
• I've added a test(s) to validate changes in this PR, or this PR only contains semantic changes.
• All existing tests are passing.