java: Add JNI bindings to adbc.h

[danepitkin]

What feature or improvement would you like to see?

Add JNI generic bindings to the Java API in java/core and java/driver-manager. This generic set of bindings will allow Java users to use any ADBC driver written that also supports the C interface e.g. C++ & Go drivers.

[vibhatha]

@danepitkin Let's correct the adbc.h path to https://github.com/apache/arrow-adbc/blob/main/go/adbc/drivermgr/arrow-adbc/adbc.h, I think it has changed after this issue was created.

Also I would assume the all the methods marked ADBC_EXPORT are the methods to be exposed via JNI or do we have a subset of methods we would like to see first?

[lidavidm]

Look at it the other way, you would implement the java interfaces via JNI calls

[vibhatha]

Right, I am pretty new to the driver API here, is there a reference that I can take a look at and determine the Java interfaces we need?

[danepitkin]

Updated! Thanks for letting me know the link was broken. I added links to the Java APIs that we would want to implement in JNI.

[vibhatha]

Thanks @danepitkin I will take a look.

[lidavidm]

This would be useful to get access to Snowflake/BigQuery/PostgreSQL (with proper performance/features) from Java.