[BUG] Names don't adhere to plugin naming convention

[mnkugler]

Also, as per opensearch-project/opensearch-build#2188, we should adjust the folder and move build.gradle, etc. to the root folder of the repo.

Do you have any additional context?
Referred to here:
opensearch-project/opensearch-plugins#174

[lezzago]

We do have the build.gradle in the root folder of the repo. We have additional ones in other folders as those are sub projects of the package.

[lezzago]

Once Alerting onboards with job scheduler, we can remove the core package and then move the build.gradle file from the alerting subproject.

[lezzago]

dependent on #19