feat: add `%get_all_stdlib` builtin function

[The-Lum]

Hi,

(To continue #1689, and thanks to be69889e :+1:)

Here is a PR in order to add a %get_all_stdlib builtin function on PlantUML.

Inspired by: https://github.com/plantuml/plantuml/blob/be69889e7f4450de7458ea45ac206f97ab3c9c79/src/net/sourceforge/plantuml/preproc/Stdlib.java#L435-L443

Here are the different outputs of %get_all_stdlib:

• Without argument: it returns a JsonArray of all the stdlib libraries names
• With whatever one param.: it returns a JsonObject with the below structure:

  {
  "stdlib_name": {"name": "stdlib_name", "version": "stdlib_version" , "source": "stdlib_src"},
  ...
  }

---

:round_pushpin: Before merge:

• Could you have just a look?

Because I changed certain class methods from "private" to "public" on: https://github.com/plantuml/plantuml/blob/be69889e7f4450de7458ea45ac206f97ab3c9c79/src/net/sourceforge/plantuml/preproc/Stdlib.java#L338 https://github.com/plantuml/plantuml/blob/be69889e7f4450de7458ea45ac206f97ab3c9c79/src/net/sourceforge/plantuml/preproc/Stdlib.java#L454 https://github.com/plantuml/plantuml/blob/be69889e7f4450de7458ea45ac206f97ab3c9c79/src/net/sourceforge/plantuml/preproc/Stdlib.java#L458

• Is it possible?

Another question:

• Where is send the Logme exception message?
• Is it necessary to add also Log or Log.error to the stdout?...

Regards, Th.

[arnaudroques]

• Could you have just a look?

Because I changed certain class methods from "private" to "public" on: [...]

• Is it possible?

Yes, that definitively makes sense!

Thanks for this new function! But now you have some more works: you have to update the documentation :-)

• Where is send the Logme exception message?
• Is it necessary to add also Log or Log.error to the stdout?...

This logging management is not very clear: we probably have to merge the two classes. However, before doing that, I think we have to open a discussion about how PlantUML should log its messages...