MOD-13177 add support for RERANK parameter in HNSW disk

[BenGoldberger]

Describe the changes in the pull request

add support for rerank config

Which issues this PR fixes

1. #...
2. MOD...

Main objects this PR modified

1. ...
2. ...

Mark if applicable

• This PR introduces API changes
• This PR introduces serialization changes

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Note

Medium Risk
Adds new query-parameter parsing for disk-based HNSW and changes query-param initialization semantics, which could affect runtime query behavior if incorrectly gated or defaulted.

Overview
Adds support for a new RERANK runtime query parameter for disk-based HNSW: introduces VecSimCommonStrings::HNSW_RERANK_STRING, a TRUE/FALSE validator, and resolver logic that initializes hnswDiskRuntimeParams.shouldRerank to VecSimBool_UNSET and rejects RERANK on non-disk or non-HNSW indexes.

Refactors VecSimIndex_ResolveParams to use basicInfo().isDisk and a dedicated _InitQueryParams initializer instead of a raw zeroing, and adds test-only setIsDiskForTesting plus new unit tests covering defaults, acceptance/rejection, and error paths for RERANK on “disk” vs RAM HNSW.

Minor follow-ups: fixes TieredSVSIndex::debugInfo() to use the boolean result of atomic_flag::test(), and updates tiered-info tests to compare backgroundIndexing against VecSimBool_TRUE/FALSE.

^{Reviewed by Cursor Bugbot for commit e26e87e. Bugbot is set up for automated code reviews on this repo. Configure here.}

[jit-ci]

🛡️ Jit Security Scan Results

✅ No security findings were detected in this PR

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^{Security scan by Jit}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.90%. Comparing base (5bcc53e) to head (e26e87e).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #943      +/-   ##
==========================================
+ Coverage   96.71%   96.90%   +0.19%     
==========================================
  Files         129      129              
  Lines        8057     7683     -374     
==========================================
- Hits         7792     7445     -347     
+ Misses        265      238      -27     

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[GuyAv46]

bzero is actually deprecated. Consider taking this opportunity and replacing it with memset.