[Concept] Epoch - add exercise templates

[zhravan]

Add exercise templates and tests for Epoch.

Acceptance criteria:

• Add templates under internal/exercises/templates/
• Add tests under internal/exercises/templates/
• Add to internal/exercises/catalog.yaml
• Provide helpful hints in catalog.yaml

[Omesh2004]

i have done a pr for this issue pls review .Wanted to learn the basics of Go

[Omesh2004]

i think the issue can now be closed ...after my latest pr