Support custom link for Bitbucket Comment Reporter

[cfsb-jrose]

Is your feature request related to a problem? Please describe.
We're using https://megalinter.io/latest/reporters/BitbucketCommentReporter from a Jenkins pipeline and would like the ability to override the default link so we can reference the Jenkins build instead of a Bitbucket pipeline.

Describe the solution you'd like
Environment variable that could override the link programmatically defined by the Build Id. If environment variable is not defined, use existing logic to make the link.

Describe alternatives you've considered
N/A

Additional context
We use Jenkins for CI/CD with Bitbucket for SCM.