chore: Adding GitHub Actions Workflows

[yhakbar]

Description

Adds GitHub Actions workflows to cover the linting and testing of this project.

Specifically does not test functionality that requires AWS or SSH configurations, as those have been cordoned off to separate files requiring build flags to test to ensure that tests work out of the box without additional setup.

As part of that work, changes were made to the source code to address lint findings and to isolate code paths that involved AWS or SSH integrations.

The logic involved in leveraging the version of Boilerplate in templates was also refactored so that the version could be mocked in tests, removing the explicit dependency on setting the version through a linker flag.

TODOs

Read the Gruntwork contribution guidelines.

• Update the docs.
• Run the relevant tests successfully, including pre-commit checks.
• Ensure any 3rd party code adheres with our license policy or delete this line if its not applicable.
• Include release notes. If this PR is backward incompatible, include a migration guide.

Release Notes (draft)

Added / Removed / Updated [X].

Migration Guide