Chore: Update Dependabot Configuration and Libraries for MXD Backend Service

[ieuna]

WHAT

• Previously in the existing DEPENDENCY file, only npm libraries were listed. But MXD now has Java code, so Java libraries should be listed as well.
• In the dependabot configuration file, gradle path was scanning root folder. There is no gradle config in root folder. It needs to scan backend service root folder to suggest version update for Java libraries.

Acceptance Criteria

1. Add dependabot configuration for mxd backend service.
2. Add Java dependency list for backend service