feat: add config for running in a date window

[fryz]

Description

Add a startDate and endDate parameters, which are used to configure the behavior of executing the auto-comment workflow. Either or both startDate and endDate can be provided, and the current time is checked agains these dates to determine if the workflow can be executed.

The startDate and endDate parameters are not required, and as such, this feature is backwards compatible.

Motivation and Context

I want to support the case where we auto-comment only within a specific date-window. For example, if the company is on a company-wide holiday, I want to configure the auto-commenter to message out that the company is on break and what that means for providing support during this time.

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Enhancement (changes that improvement of current feature or performance)
• [ ] Refactoring (changes that neither fixes a bug nor adds a feature)
• [ ] Test Case (changes that add missing tests or correct existing tests)
• [ ] Code style optimization (changes that do not affect the meaning of the code)
• [ ] Docs (changes that only update documentation)
• [ ] Chore (changes that don't modify src or test files)

Self Check before Merge

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [ ] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.