Feature: make configurable status check on coverage drop or add a kind of "tollerance"

Hi,

First, thanks a lot for your work in this plugin, it's very useful for my organization even if code coverage reporting is a ~stressful~ topic.

I noticed that from version [2.1.1](https://github.com/jenkinsci/github-pr-coverage-status-plugin/releases/tag/github-pr-coverage-status-2.1.1), is present the possibility to

> Fail the status check when the coverage decreased

which is great and a fair point of discussion for the proposed code in PR but sometimes the report show something like that:


which generate a bit of confusion and some awful discussion. I think that the reported value is truncated but the status check is evaluated with the complete value. Maybe a solution could be:

- evaluate the status with the same value reported in the PR
- add the possibility to disable the commit status or configure a tollerance value in which the status check is successful or failed.

Again thanks a lot for your work!