Replace maven by gradle

[dblock]

Is your feature request related to a problem? Please describe.

When working with multiple plugins, such as when making a patch release, security plugin is a 1-off and creates unnecessary friction.

See opensearch-project/opensearch-plugins#119 and https://github.com/opensearch-project/opensearch-build/blob/main/scripts/components/security/build.sh#L70 as examples.

Describe the solution you'd like
Replace maven with standardized gradle implementation just like all the other plugins in OpenSearch.

[davidlago]

#1121 was a first attempt at this.

This PR is outdated and it does too many things: move CI to gradle, upgrade gradle version, update tests (apparently this last one was more involved as it introduced a new runner)...

We are prioritizing work on our test suite, to start using the OpenSearch Test Framework, and moving to gradle is part of that initiative. That said, @cliu123, do you think there is a subset of that PR that we could merge, moving to gradle while leaving the tests mostly unchanged until we tackle that larger body of work?

[rs-eliatra]

PR: #1592

[prudhvigodithi]

Hey I can see the security component build system uses gradle, can this issue be closed? :)
@dblock @davidlago @rs-eliatra @bbarani

[peternied]

Thanks for noticing!