Make the first calculator argument optional

Key Features

• Make the first calculator argument optional (justFinishedExecutionDurationMs), to avoid TypeScript and linting errors from unused arguments when irrelevant.

README and Documentation improvements

Key Features

• README: Added a Table of Contents for easier navigation.
• Documentation: Typo fix along with some refinements.

Increase unit test coverage

Key Features

• Increase unit test coverage, specifically for error-throwing job scenarios.

Method `waitTillCurrentExecutionSettles` was renamed

Key Features

• Breaking change: Method waitTillCurrentExecutionSettles was renamed to waitUntilCurrentExecutionCompletes.
• README, Unit Tests and Documentation were improved.

Non breaking quality improvements

Key Features

• Making the error type generic for flexibility.
• Improved docs.
• Implementation detail: undefined type is used instead null.

Upgrade Target Compatibility to ES2020, README and Unit Tests refinements

Key Features

• Upgrade Target Compatibility to ES2020.
• README refinements, including a section about the potentially breaking change in version v2.0.0.
• Unit Tests refinements: adjusting indentation to be 2 spaces, and refining some comments.

Improved README

Key Features

• Improved README: adding a time-based example, and clarifying differences between time-based and interval-based policies.

README refinements

Key Features

• README refinements.

README refinements

Key Features

• README refinements.

Updating dev-dependencies

Key Features

• Updating dev-dependencies.