Add GitRemotes() and GitRemote() aliases (#147)

[ap0llo]

Add aliases to retrieve information about a git repository's remotes.

• GitRemotes(): List all of a repository's remotes
• GitRemote(): Get a specific remote by name (or null if no such remote exists)

It was already possible to get the remotes indirectly via the GitBranchCurrentAlias() but I found this counterintuitive and hard to discover.

I think it makes sense to have dedicated aliases for working with remotes as this git functionality is not directly tied to any branch.