Allow using more than one language server at a time within a file

[leungbk]

When working with JavaScript, it is common to want to run the vscode-eslint server for diagnostics, while running a more general-purpose server like the Flow or TypeScript server for definition-hopping and the like.

lsp-mode.el supports this kind of set up. It would be nice if eglot did as well.

[joaotavora]

There are multiple issues for this, try to find the active one and let's close this one. By the way, you can have multiple flymake backends. I have an eslint Flymake backend which can coexist with a language server managed by Eglot. But I agree this is a desirable feature. So closing this one, and it's up to you to search the issue archives and link this with the existing issues. Thank you.