Add support for MATLAB language server

[JohnC32]

This adds support for the MATLAB Language Server, https://github.com/mathworks/MATLAB-language-server

[JohnC32]

I see 2 checks failed. I looked an they seem to be unrelated to my changes. They are:

In toplevel form:
lsp-completion.el:187:16: Error: ‘when-let’ is an obsolete macro (as of 31.1); use ‘when-let*’ or ‘and-let*’ instead.
...........................Test lsp-byte-compilation-test backtrace:


Test lsp-byte-compilation-test condition:

    (ert-test-failed
     ((should (byte-compile-file library)) :form
      (byte-compile-file
       "/Users/runner/work/lsp-mode/lsp-mode/lsp-completion.el")
      :value nil))

[jcs090218]

I see 2 checks failed. I looked an they seem to be unrelated to my changes. They are:

Yeah, those are unrelated. There's no need to worry about it.

[jcs090218]

Can you update docs/lsp-clients.json as well? Thanks!