Add getAnnotations function to plugin and remove _getState private one

[stockiNail]

This PR is adding getAnnotations function to annotation plugin to get all annotation elements created for a chart.
It also removes _getState` function from annotation plugin because it was used for testing and it was the only way to access to the elements instances.

TODO

• test cases
• types
• documentation

[davidnir1]

Hello @stockiNail,
Is there an ETA on this PR (if approved)?
We're trying to prioritize tasks and this solves a big one for us :)
Thanks!

[stockiNail]

Is there an ETA on this PR (if approved)?

@davidnir1 it's planned to be released in version 3.1.0 (next one if we will not have any bug in the meantime). There are other PRs tagged for 3.1.0 therefore additional time is needed but depends on the maintainer, we could also think to move some PRs to 3.2.0 and then try to release version 3.1.0 earlier.

[tomasbeloch]

Hello @stockiNail, is there some plan in place when you're planing to merge this one? It would be great to allow the tooltips over the box annotations. Thanks!

[stockiNail]

@tomasbeloch I don't think so, I'm a collaborator not a maintainer ;) Furthermore I'm currently busy in another important project therefore my time is very limited. I'm very sorry. I hope to have time soon to restart working on this project.
@kurkle what do you think?