Provide LMDB index recommendations in explain plans

[hmottestad]

GitHub issue resolved: #5553

Briefly describe the changes proposed in this PR:

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PR Author Checklist (see the contributor guidelines for more details):

• my pull request is self-contained
• I've added tests for the changes I made
• I've applied code formatting (you can use mvn process-resources to format from the command line)
• I've squashed my commits where necessary
• every commit message starts with the issue number (GH-xxxx) followed by a meaningful description of the change

[Copilot]

Pull Request Overview

This PR implements index recommendation functionality for LMDB database queries. The feature analyzes query patterns and suggests optimal indexes when the current index requires a full scan, helping users identify performance optimization opportunities.

Key Changes

• Added index name tracking through the IndexReportingIterator interface implementation
• Implemented recommendation logic that evaluates candidate indexes based on usage count, pattern score, and order deviation
• Created comprehensive test coverage for all index permutations and recommendation scenarios

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
LmdbExplainIndexRecommendationTest.java	New test file validating index recommendation logic across all permutations and preference scenarios
RecordIterator.java	Added getIndexName() default method to support index name retrieval
LmdbStatementIterator.java	Implemented IndexReportingIterator interface to propagate index names
LmdbRecordIterator.java	Core implementation of index recommendation algorithm with candidate selection and tracking
TripleSourceIterationWrapper.java	Delegated getIndexName() to wrapped iterator when available
StatementPatternQueryEvaluationStep.java	Added explicit null handling when setting index names on statement patterns

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[Copilot]

The condition on line 307 checks contextBound again, but this code is inside the else block where contextBound could be true (lines 300-320). This creates a logic issue where the order of 'c' could be duplicated. The condition should only add 'c' if it hasn't been added already, or this appears to be redundant since line 317 already checks and adds 'c' if contextBound is true.

Suggested change

	if (contextBound) {
	order.add('c');
	}
	// Removed redundant addition of 'c' to avoid duplication.

[Copilot]

The condition if (contextBound) on line 307 is redundant because it's already inside a block where contextBound is guaranteed to be true (line 300). The check is unnecessary and reduces code clarity.

Suggested change

	if (contextBound) {
	order.add('c');
	}
	order.add('c');