Provide way to add/delete/clear tags

[AnWeber]

Is your feature request related to a problem? Please describe

I use mani to manage a lot of repositories. Since I also frequently change my working/ active repositories, I would like to simply define "active" tagged projects where I can execute tasks faster (mani run --tags active ...). I want to prevent to execute some long running tasks on not needed projects.

Describe the solution you'd like

I would like to have extended the CLI which supports CRUD methods for tags (similar to kubectl, kubectl get/create/delete deplyoments )

• mani add tag <tag> --project - add tag to project in mani.yaml. --project is optional and could also be retrieved using current dir (compare with project dir)
• mani remove tag <tag> --project - remove tag of project in mani.yaml. --project is optional and could also be retrieved using current dir (compare with project dir)
• mani clear tag <tag> remove tag of all projects

Additional context

• That the YAML parser removes the comments (addressed in Provide a way to add projects.  #43) is not important for my use case. A setting allowAutomaticOverride: true could be added to the mani.yaml. If this setting is not present, the tag is not added and a warning message is displayed with a hint for this setting. If it is true, override of mani.yaml is accepted.
• The feature can also be implemented without mani change. Necessary helper methods can be implemented easily. But I would find a support in the context of mani handy, but time consuming to implement.

Off Topic

I was looking for a tool to easily manage my repos, but everyone was forcing me in a direction I didn`t want. mani is very flexible and a great timesaver. Therefore a big thank you.

[alajmo]

I like this feature, but as mentioned in the other issue, it's quite a complex task and I wouldn't want to add the allowAutomaticOverride since people would first stumble upon the mani clear tag command and try to do it, then get hit with a warning that it's not possible, so it's not the most UX friendly. I would like for it to work with comments as well, and perhaps with some work it could:

• https://github.com/vmware-archive/go-yaml-edit
• https://stackoverflow.com/questions/55674853/modify-existing-yaml-file-and-add-new-data-and-comments

However, my bandwidth is limited at the moment, I'm focusing on https://github.com/alajmo/sake at the moment, but after it's done, I will port back a lot of changes and will then perhaps start working with this feature, unless you're open to working on this then I'm happy to discuss how to implement this.

[AnWeber]

More time would always be nice. But thanks for including it in the backlog.