Port over Spatial-K release mechanism

[sargunv]

I created the tag slightly differently for v0.12.0 and it broke the release process.

My newer libraries have a slightly different mechanism; they trigger a release directly from Github Actions, with the tag created there, the same way every time. We should port over that release process (could copy it from Spatial-K).

We can also port over the snapshot release process, moving snapshots to Maven instead of GHA for ease of use.