[IN-31] ci: add needed actions

[sw-wayner]

Add required actions for PR Preview

These actions would

• build and publish a Docker image with every push to the branch
• add preview label when the PR is ready_for_review (this triggers the app creation)
• clean up the created app whe the PR is closed
• build and publish a Docker image when the PR is merged
• enable slash commands to check and update the created environment

Note

This PR needs this secrets to be configured in order to work

• PAT - A GitHub Personal Access Token with following scopes repo:status public_repo.
• DOCKERHUB_USERNAME - The username for the DockerHub account.
• DOCKERHUB_TOKEN - The token for the DockerHub account.