Create guidelines for creating interfaces of tools (modules)

[wenzeslaus]

We are missing a guidelines on how to create interfaces for individual tools, specifically how to do name parameters and use parser features well to define the interface. While the current documentation covers basic how-to, it does not cover best practices. Various decisions about how to do things are not captured either.

Starting point already covering parts of standard options and options versus flags discussion:

Developing custom GRASS tools (FOSS4G 2022 workshop): Best Practices

Most recently, this came up in https://github.com/OSGeo/grass/pull/2189#discussion_r1383520517.

[nilason]

~~Related: https://github.com/OSGeo/grass/issues/1125~~

Rereading the description, now I see this is about interface as in API, not GUI. Sorry about the noise.