Add CI Provider for Bitbucket Pipelines

[ChrisTitos]

This adds Bitbucket Pipelines as a CI provider.
I copied the code from one of the other providers, but didn't see any existing tests for this (but it's a quite straightforward change I guess)

This is a

• Feature

By submitting this pull request I confirm I've read and complied with the below requirements 🖖

• I have used Preevy for a while and am familiar with the function it provides.

If this is a bug fix or feature:

• I tested the proposed change on my cloud provider: Please specify which provider
• I tested the proposed change on a local Kubernetes cluster.

Both are n/a