Storage: Refine VectorIndexHNSW -> VectorIndex

[breezewish]

What problem does this PR solve?

Issue Number: ref #9032

Problem Summary:

What is changed and how it works?

1. VectorIndexHNSW -> VectorIndex

We dont need user to list HNSW explicitly. Prepare for AUTOINDEX.

2. VectorIndexWriter -> VectorIndexWriterInMemory & VectorIndexWriterOnDisk

This is to be aligned with FullTextIndexWriterInMemory|OnDisk.

Previously we always construct inMemory and optionally write to disk.

Now user must explicitly choose inMemory or onDisk when constructing the writer (although for the vector onDisk we still construct inMemory) because FTSIndex support fully construct ondisk.

3. LocalIndexViewer -> ICacheableLocalIndexReader

• Viewer -> Reader, because it may be either inMemory or onDisk. "View" only stands for the mmap way and is not a correct word for it.

• I: stands for a pure abstract base class (i.e. Interface) that meant to be derived instead of constructed directly. Similar to IColumn.

• Cacheable: I think we only need it to provide necessary methods when put inside a LocalIndexCache. There is no need to put other common parts for a LocalIndexReader here. I expect to only have methods like getMemoryCost, etc. So let's call it ICacheableLocalIndexReader.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JaySon-Huang, Lloyd-Pottiger

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-02-28 08:20:30.407208833 +0000 UTC m=+603178.360367100: ☑️ agreed by Lloyd-Pottiger.
• 2025-03-03 02:17:38.975329521 +0000 UTC m=+235172.104249264: ☑️ agreed by JaySon-Huang.