Allow using git tags with seed-jobs

[DaniJG]

Describe the solution you'd like
I would like to be able to configure the seed jobs to use a specific git tag of the repo.
Currently the Jenkins CRD allows you to specify the repositoryBranch of the created seed jobs, so you could in theory point it to the right tag using refs/tags/<tagName>

 seedJobs:
   - id: my-seed-job
     targets: ...
     description: ...
     repositoryBranch: refs/tags/my-tag
     repositoryUrl: ...

However this doesnt work because the git SCM of the seed job is configured to not pull tags.
This is because the groovy script created for the seed job initializes the extra options for gitSCM as follows (source here):

def gitExtensions = [
	new CloneOption(true, true, ";", 10),
	new GitLFSPull()
]

Where the second boolean of the CloneOption constructor corresponds with the noTags parameter: https://javadoc.jenkins.io/plugin/git/hudson/plugins/git/extensions/impl/CloneOption.html

Ideally the Jenkins CRD would include a new optional boolean parameter to enable fetching of tags in the seed job (defaulted as false), which would be used to control the second boolean parameter of the CloneOption in the generated groovy script:

 seedJobs:
   - id: my-seed-job
     targets: ...
     description: ...
     # using tags is now possible by also including fetchTags: true
     repositoryBranch: refs/tags/my-tag
     fetchTags: true
     repositoryUrl: ...

def gitExtensions = [
        // noTags parameter set as true only when FetchTags is false, and viceversa
	new CloneOption(/* shallow */ true, /* notags */ {{ ! .FetchTags }}, /* reference */ ";", /* timeout */ 10),
	new GitLFSPull()
]

Describe alternatives you've considered
You can only use git branches as the source for the seed job. There is no alternative that lets you use git tags other than manually updating the created seed job to allow fetching tags (but that gets lost if the operator reinitializes jenkins)

Additional context
N/A

[brokenpip3]

Make sense, great write-up. Will add this fr in the 0.9 queue.