Introduce explicit index field matching methods

[DragonFSKY]

Closes #5187

This PR follows the defensive path proposed in the issue discussion for IndexInfo.isIndexForFields(Collection<String>).

The existing method is deprecated but keeps its current subset-matching behavior for compatibility. The PR introduces explicit alternatives for the different matching semantics:

• containsAllFields(Collection<String>) for subset matching regardless of index field position
• isIndexForFieldsExactly(Collection<String>) for exact field-name matching regardless of order
• coversFields(Collection<String>) for compound-index prefix coverage

It also updates an internal test helper to use containsAllFields(Collection<String>) instead of the deprecated method.

Tested with:

./mvnw -s settings.xml -pl spring-data-mongodb clean test -Dtest=IndexInfoUnitTests

Checklist:

• You have read the Spring Data contribution guidelines.
• You use the code formatters provided by the project and have not submitted unrelated formatting changes.
• You submit test cases that back your changes.
• You added yourself as author in the headers of the classes you touched.