[Applications] Use git2go instead of go-git for git based helm repo

[dharapvj]

Description of the feature you would like to add / User story

Currently, for Applications feature, to pull helm chart from git repo, KKP uses go-git library.

But, using git as source for helm chart does not work with Azure Devops based Git repo since Azure has not implemented "classic" git protocol and has only deployed multi_ack protocol. [Citation for this claim in tickets linked below]

We received errors on ApplicationInstallation like below:

Events:
  Type     Reason                                  Age                   From                             Message
  ----     ------                                  ----                  ----                             -------
  Warning  ApplicationInstallationReconcileFailed  73s (x17 over 6m52s)  kkp-app-installation-controller  handling installation of application installation: failed to download application source: failed to clone repository: empty git-upload-pack given

So until go-git library resolves issues to use it with Azure DevOps, Applications using helm charts from Azure-Devops git repo is not possible. Azure-Devops support for enterprise customers is important.

Flux team has had a temporary fork for go-git which allowed azure devops to work but the fork is now archived so we are not sure if this a right solution. Eventually, flux team went to use git2go library instead of go-git..

Considering that go-git issues are almost 4 years old - it is unlikely to get fixed anytime soon so we should consider migrating to git2go library for clone git (which also supports Azure DevOps)