go/devtools-memory-page-vision

Build:

• crud for snapshots
• fakes for memory page
• show snapshot stats
• show diff stats
• show diff details
• export to CSV
• filter by class / library
• Move button 'Clear'
• Preserve sorting between data sets of classes and pathes

Clean up:

• experiment with Gallery
• test cover
• in-app documentation - http://go/devtools-snapshots-help-wording
• release notes - http://go/wording-for-memory-diff-release-notes
• UX research - go/devtools-memory-diff-ux-research
• audit analytics events and perf counters - Configure GA for memory screen. #4705

After MVP clean up:

• update documentation: Update documentation for DevTools > Memory website#7830
• clean up retired code