Fixes #3917: Add package openapi naming strategy.

[jgiles]

Support passing "package" for openapi_naming_strategy to create in-package unique names by qualifying nested types.

This strategy operates like "simple" except that we start by qualifying nested types, so that nested type names stay stable as new types are added in the same package.

We rely on package and type naming conventions to identify where the package name ends and the nested type name begins. This is not ideal, but avoids a larger refactor to provide package and type names as separate inputs to all the name resolution strategies. Longer term, that refactor may be desirable.

[johanbrandhorst]

Looks great, just a minor question. I'm starting to think that we need a whole docs page for the different types of name resolutions that exist but you don't need to add it here.

[johanbrandhorst]

Could we move this regexp compilation into a global variable?

[jgiles]

Sure!

I actually had it as a global var initially, as is often done for regexp compilation... but I moved it into the function to have the pattern defined in the same context as it's used for readability. Generally name resolution only happens once per process anyways, so I don't think the performance optimization of doing the regexp compilation one time up-front really gains us anything here.

I've moved it out though into a global var though, let me know what you think.

[johanbrandhorst]

Thanks, I appreciate the explanation. All the same, I think anyone reading an inline regexp.MustCompile will be surprised, so lets leave it as a package level variable.

[johanbrandhorst]

Thanks for your contribution :)!