Use custom java toolchain from @graknlabs_build_tools (#5208)
Use custom java toolchain from @graknlabs_build_tools (#5208)

## What is the goal of this PR?

Due to usage of Java custom toolchain (defined in [`graknlabs/build-tools`](graknlabs/build-tools)), "Go to implementation" (**Cmd+Click** on class name) action in IntelliJ IDEA now correctly takes developer to source code (`*.java` files). Previously, such action would result in going to `*.class` files, which hampered developers' productivity.

## What are the changes implemented in this PR?

Fixes graknlabs/grakn#4851

graknlabs/grakn,lolski/grakn,graknlabs/grakn,lolski/grakn,lolski/grakn,graknlabs/grakn,lolski/grakn,graknlabs/grakn