Add support for Java bindings

[seonWKim]

Purpose of this PR

• Add support for Java (as Java has an extensive community)
• Enable Limbo to be provided as a Java library in the future.

Changes

• Added bindings/java directory.
• Created src package for Java (Gradle) and rs_src for Rust JNI code.
• Implemented basic functionality to gather feedback and proceed with further development.
  • Some features just printout the result for testing purposes.

Future Work

• Integrate CI to publish the library.
• Enhance error handling mechanisms.
• Implement additional features and functionality.
• Add test code after we decide on which features to provide

Issue

#615

[seonWKim]

the force push made some mess 🙏

[seonWKim]

for debugging purposes, we can remove later stage on development

[seonWKim]

for debugging purpose, let's remove it at later stage of development

[penberg]

Hey @seonWKim, awesome, thanks for doing this! I will review this and happy to merge as a nice incremental step! However, I think the path for Java ecosystem is to turn this into a JDBC driver, similar to https://github.com/xerial/sqlite-jdbc.

[seonWKim]

@penberg Thanks for the review. I should look into that project. 🙏

I think this PR can be a wrapper for native functions supported by limbo as sqlite-jdbc did.

• NativeDB.c
• NativeDB.java

After deciding on which native functions to support(maybe similar to sqlite-jdbc), we can separate the java bindings to another repository(a long future work maybe). Currently I've added features by referring to python bindings.

[penberg]

Hey @seonWKim, no, I think it's good that the bindings are in the same tree because it allows more people to work on it!

The comment about JDBC is mostly about what the interface of the Java bindings should be. You almost certainly want to expose things as JDBC because that's what the rest of the ecosystem uses. The sqlite-jdbc project was just an example of how people do that in the SQLite ecosystem.

[penberg]

Merged, by manually folding the commits into one.