Enhance checking last commit for git functions

[pPrecel]

Description

Check if it's possible to check the last commit for the function's remote without cloning the whole repository. The current code is costing a lot of memory. To improve that, we can use the current library to build a solution similar to the previous solution based on the libgit2 library.

Code example:

func GetLatestCommit(url, reference string, gitAuth *GitAuth) (string, error) {
gitRepo, _ := git.Init(memory.NewStorage(), nil)
newRemote, _ := gitRepo.CreateRemote(&config.RemoteConfig{
    // implement
})
_ = newRemote.Fetch(&git.FetchOptions{
    // implement
})

ref, _ := gitRepo.Reference(plumbing.ReferenceName(reference), true)
return ref.Hash().String(), nil
}

Reasons

Speed up while process and decrease memory and CPU consumption to avoid problems like this.

[pPrecel]

Another idea is to implement a caching mechanism for the git metadata, so as not to clone/fetch the whole repo every reconciliation.

Maybe we should also re-implement the git package to work in a separate go-routine. Right now, reconciliation is waiting for every git operation that may take a lot of time. We should consider adding functionality that will allow us to request git operations in a separate goroutine, and ask fo result next time during the next reconciliation.

[pPrecel]

This issue should be implemented only if possible (this issue is an experiment, and we are ok with failure):

• enhance the git library code to calculate the last commit without cloning
• last commit check should be run in a separate go-routine, and the main reconciliation loop should not wait for it (should be requeued with a specific time)
• commit checks can be run in a centralized place in code, run once for every repository (not for every function)