JAVA-5736: Add bsonNamingStrategy option to support snake_case naming strategy

[leesungbin]

Ticket

JAVA-5736

Description

This PR adds bsonNamingStrategy property to BsonConfiguration to support snake_case naming strategy.

Testing

ran ./gradlew check

[nhachicha]

Hi @leesungbin
Thank you for the PR! We really appreciate your contribution.

However, the current Regexp-based approach doesn’t fully account for all use cases. According to the Kotlin language specification, variable names can include Unicode characters, such as Cyrillic characters. For example, a variable name like имяПеременной would not be handled correctly.

Additionally, backtick names (e.g., `my Class`) won’t be transformed as expected.

A possible refactor could leverage the existing implementation of SnakeCase in kotlinx.serialization. You can refer to this implementation:
SnakeCase in kotlinx.serialization.

Also, please ensure the tests align with the transformation rules and acronyms defined in:
JsonNamingStrategy Transformation Rules.

Looking forward to your updates! Let me know if you need any clarification.

[leesungbin]

Hello @nhachicha, thanks for providing such detailed comments.

I have copied the convertCamelCase logic from the kotlinx.serialization library and used it to convert camelCase to snake_case.

Additionally, I introduced an error condition for scenarios where decoding snake_case to camelCase is ambiguous (for instance, my_http_auth could be interpreted as myHttpAuth or myHTTPAuth).

Please give it a look. Thanks!