Increment version to 2.12.0-SNAPSHOT and change imports to align with core lucene upgrade

[ryanbogan]

Description

Combination of #1211 and backport of #1147

CI will not pass unless both are combined on the branch.

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed as per the DCO using --signoff

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[martin-gaievski]

Why we're combining backport and infra changes? Say comparing this PR with merging #1211 and converting this one to just a backport. I think separate PRs give better visibility on history of changes

[heemin32]

Why we're combining backport and infra changes? Say comparing this PR with merging #1211 and converting this one to just a backport. I think separate PRs give better visibility on history of changes

I guess, build will fail with only either of the change. Therefore both changes are needed in single PR.

[ryanbogan]

Why we're combining backport and infra changes? Say comparing this PR with merging #1211 and converting this one to just a backport. I think separate PRs give better visibility on history of changes

In order to do that, we would have to merge a PR with all tests failing. There will be compile errors if either one of the PR's is merged alone.

[martin-gaievski]

that makes sense, let's merge this PR