Features/sma 117 GitHub actions

[Aboudjem]

This PR adds:

Templates for PRs, bugs, and feature requests to make things uniform.
GitHub Actions for better code quality, lint & test checks, and to clean up stale items.

[linear]

SMA-117 Setup branch protection, PR template, CI pipeline for scw-contracts

Github Repo: https://github.com/bcnmy/scw-contracts

Goal is to setup

1. Branch protection rules where no push can be made directly to main branch.
2. Add a PR template
3. Make signed commit mandatory and each PR requires at least 2 approval for merging.
4. Setup CI pipeline where with each PR, test cases are run with coverage.