Adding the stringSplit macro to the Go template component

[xenbyte]

When utilizing Cloudprober's Go template component to generate configuration files, a scenario arose in which I required the capability to divide a pre-defined string into a slice of strings. Regrettably, the absence of a suitable macro impeded this process. As a solution, I have introduced the stringSplit macro, which seamlessly employs the strings.Split() function to accomplish this task.

[manugarg]

Thanks for the PR, @xenbyte!

Please see the inline comments.

[xenbyte]

Hey @manugarg, just a heads up that I've removed the comments from the code document due to ongoing formatting glitches in my editor. It was causing some significant changes in the diffs. Also, I realized that my initial code description might not be exactly what you're looking for. So, if you could take a look and add your description, that'd be awesome! Thanks!