Prepare repository for multi-contracts development

[matjazv]

What was the problem?

This PR resolves #1.

How was it solved?

• Directory structure is ordered in a way to offer easy navigation and multi contracts development.
• GitHub action is configured to be triggered after each PR is created and to be merged with the main branch.
• Issues and Pull request have templates.
• README.md file exists and has some basic information regarding this repository and how to install and deploy smart contracts to the private test network.
• Initial code for Lisk L1 token was developed (more for a demo purpose and as an example then following any decision made by the team).
• Some unit tests were developed for the same reason as initial code for Lisk L1 token.

How was it tested?

• GitHub action and templates for issues and pull requests were tested on a private repository.