Support table level write buffer size

[evenyag]

What type of enhancement is this?

Refactor

What does the enhancement do?

Currently, all tables share the same global write buffer. A large table may stall other small tables due to the high write buffer usage.

We may want to limit the max buffer size a table could use.

Implementation challenges

1. Should we set a table level write buffer by default?
2. What's the impact on compaction?