Technical Documentation for Hilla Parser

[taefi]

This technical documentation should be part of the repository as a markdown document, available for the contributors as well as the maintainers, describing the overall overview of how the feature is working:

• What are the inputs and outputs of the Hilla Parser?
• What are the related packages/plugins and what features relaying on which package/plugin?
• What are the important lifecycle methods? What's their order of execution?
• How is it related to the Hilla generator?

When writing about the above bullet points, we strive to answer the following questions:

• Why any element of this feature is implemented this way?
• What were the motivations and limitations that led us to the current design/implementation?

This calls for a design document to describe the overall Hows and Whys, and should only mention Classes, Files, APIs to the extent that it gives enough clue to the maintainers/contributors where to look in the code when something is not working, or when we want to evaluate the possibilities for an enhancement or a behavioural change. It should avoid going further, unless there's specific logic worth explaining and only if it is not possible to do that as Javadoc/JsDoc - very rare cases.

The designated file for this documentation is a Design.md file at the root of related TS package(s) / Java module(s).