[beancount] Use the Rust version of language server

[gagbo]

The Python and Typescript versions of beancount-language-server are deprecated, the maintained version now is the Rust one.

TODO:

• Create a tutorial to help people set the path to journal file using a modeline (maybe with eval so that the absolute path to journal file is dynamically computed ??) No need for tutorial, the journal file option will default to "current buffer", so it should cover most use cases.
• Do we want to maintain legacy arguments for the older versions?

[gagbo]

It's not ready to be merged yet, I haven't had time to test it properly

[gagbo]

@jcs090218 Do you have any input on this? Pinging you as it seems you're the person who wrote the first version of the client, and I'm not sure whether there are specific maintainers to review the changes for less-used clients like this one.

[jcs090218]

There is no specific maintainer for this client. The changes look reasonable.

Have you tested it already? If this work, then this shall be merged!

[gagbo]

I only tested those with nvim now that I think about it, I'll test the changes in approx. 8-10 hours and report back!

[gagbo]

Completion's not working for some reason, I'll try to clean that up

[gagbo]

It works now, I think I should not have tried to be fancy with the journalFile default value. nil will correctly initialize to the current buffer on the server side.

[jcs090218]

LGTM! 👍

@yyoncho Can you give me higher merge permission? I get this Enable auto-merge every time I want to merge a PR. :(

[yyoncho]

@jcs090218 you are now added as admin but in general we should make this CI green.