fix(desktop): sync bookmark counts in sidebar

[Guflly]

Fixes #613

• keep sidebar bookmark counts in shared state
• update counts from chat and bookmark views
• cover count transitions

Tested with:

• ./gradlew :desktop-shared:test
• ./gradlew test
• ./gradlew spotlessCheck
• ./gradlew detekt

[CLAassistant]

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[haiphucnguyen]

Hi @Guflly Thank you for your PR. Can you sign the above CLA?

[Guflly]

Signed.

[haiphucnguyen]

There is the CLA link above, could you sign it again. Thanks!