[MRELEASE-839]: Unable to supply tag to release for release:perform

[edwardUL99]

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This PR introduces a fix which allows a tag to be supplied either using a -Dtag=<tag> flag or passing the tag into the <configuration><tag>tag</tag></configuration> section of the release plugin in the pom. The PerformReleasePojo previously incorrectly extended AbstractReleaseMojo where it now extends AbstractScmReleaseMojo. This required some small changes to the unit tests where I updated the stub files to correct a NPE error and to also assert that the ScmReleaseLabel was being populated correctly. I also added a directory MRELEASE-839 under it/projects/perform which contains the integration test for this issue.

From the Jira, the command to get the fixed changes is:

mvn org.apache.maven.plugins:maven-release-plugin:3.0.0-M7-SNAPSHOT:perform -DconnectionUrl=scm:git:https://gitlab.com/fake/r365-autoconfig.git -Dtag=0.1.14 -DuseReleaseProfile=false

Replacing the connectionUrl with correct SCM and required tag. I have tested that it works with both localCheckout set to true and false

[kwin]

see #145 (comment). This exposes a lot more unused parameters, not just tag

[edwardUL99]

@kwin I see your point. What's the best course of action? Wait for 145 to be resolved, implement the changes suggested by 145, or just add tag property to perform release mojo?

[kwin]

@michael-o Please advise how to continue.

[edwardUL99]

@kwin I see you commented on #145 to create 2 separate classes. I believe if they are created, this pull request may be made redundant