Add Support for GitHub Actions' Triggers and Events

[aweris]

Description

To enhance the accuracy with which Gale replicates GitHub Actions locally, we need to support various triggers and events. However, given the local context, certain events (e.g., external webhooks, repository dispatches) may not be feasible or logical to simulate. Our goal should be to support those that make sense in a local development environment.

Current Behavior:

• gale does not adequately simulate or recognize many GitHub Action triggers and events.

Desired Behavior:

• gale should be able to recognize and process those GitHub Actions' events and triggers that are logical to simulate locally.
• Users should have the ability to mock or manually specify feasible triggers to initiate workflows in a way that closely resembles their behavior on GitHub.

Tasks:

1. Enumerate GitHub Actions events and triggers and categorize them based on feasibility for local simulation.
2. Update gale's configuration parser to detect and handle the categorized feasible triggers and events within GitHub Actions YAML files.
3. Develop mechanisms within Gale for users to manually specify or mock these triggers and events.
4. Ensure that the processed triggers and events initiate workflows in gale in a manner resembling their GitHub counterparts.
5. Test this new capability with a variety of workflows to ensure consistent and expected behavior.
6. Enhance gale's user documentation, detailing the support for specific triggers and events and offering guidelines on how to simulate them locally.

Additional Notes:

• It's crucial to set user expectations correctly. Clearly document those triggers and events that are unsupported due to the inherent differences between a local environment and GitHub.
• An interactive CLI or potential UI can be beneficial for users to understand and select from the list of supported events or to mock triggers.
• Stay abreast of any updates or changes in GitHub Actions' triggers and events to keep Gale's functionality relevant and up-to-date.