Accept gitlab hosts w/out scheme and use https:// by default

[foot]

At the moment we have to explicitly include the scheme to the gitlab api server. e.g.

These work:

c, err = NewClient(gitlabToken, "", WithDomain("https://gitlab.works")) // "https://gitlab.works"
c, err = NewClient(gitlabToken, "", WithDomain("http://gitlab.works")) // "http://gitlab.works"

This does not work yet but should prepend https:

c, err = NewClient(gitlabToken, "", WithDomain("gitlab.works")) // "https://gitlab.works"

[foot]

Fix might go in here

gitlabBaseURL := "https://"+domain;

go-git-providers/gitlab/auth.go

Lines 215 to 245 in 78f7d82

	if tokenType == "oauth2" {
	if opts.Domain == nil || *opts.Domain == DefaultDomain {
	// No domain set or the default gitlab.com used
	domain = DefaultDomain
	gl, err = gogitlab.NewOAuthClient(token, gogitlab.WithHTTPClient(httpClient))
	if err != nil {
	return nil, err
	}
	} else {
	domain = *opts.Domain
	gl, err = gogitlab.NewOAuthClient(token, gogitlab.WithHTTPClient(httpClient), gogitlab.WithBaseURL(domain))
	if err != nil {
	return nil, err
	}
	}
	} else {
	if opts.Domain == nil || *opts.Domain == DefaultDomain {
	// No domain set or the default gitlab.com used
	domain = DefaultDomain
	gl, err = gogitlab.NewClient(token, gogitlab.WithHTTPClient(httpClient))
	if err != nil {
	return nil, err
	}
	} else {
	domain = *opts.Domain
	gl, err = gogitlab.NewClient(token, gogitlab.WithHTTPClient(httpClient), gogitlab.WithBaseURL(domain))
	if err != nil {
	return nil, err
	}
	}
	}

[dinosk]

The domain could also be parsed and have https:// prepended only if it's missing, at:

• https:/fluxcd/go-git-providers/blob/master/gitprovider/repositoryref.go#L106
• https:/fluxcd/go-git-providers/blob/master/gitprovider/repositoryref.go#L162