[no-release-notes] go/store/nbs: progress on chunk journal sync

[andy-wm-arthur]

Cleans up chunk journal life cycle to facilitate push/pull/close paths. Prior work:

• initial implementation of chunk journal: https://github.com/dolthub/dolt/pull/4878
• enforce single in-process NBS per directory: https://github.com/dolthub/dolt/pull/4848
• enforce uniqueness for chunkSources within tableSet: https://github.com/dolthub/dolt/pull/4860
• export getRecordRanges from chunkSource: https://github.com/dolthub/dolt/pull/4909

Remaining work:

• garbage collection support
• convert chunk journals at capacity to table files