feat: implement three build types for async index build

[SNC123]

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Refer to a related PR or issue link (optional)

#6756 (Tracking Issue)

What's changed and what's your intention?

As title. 🐭
Implemented three build types for async index build:

• Flush: Triggered after a flush operation.
• Compact: Triggered after compaction if new files are created.
• SchemaChange: Triggered by a schema change when a fast-path index build is required.
• Manual: Triggered manually by an administrator via the build_index('table_name') function. (In another PR)

PR Checklist

Please convert it to a draft if some of the following conditions are not met.

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR requires documentation updates.
• API changes are backward compatible.
• Schema or data changes are backward compatible.

[zhongzc]

LGTM

[evenyag]

Others look good to me.