Fix mojo LSP configuration to conform to magic introduction

[allemand-instable]

fixes mojo-lsp not working due to mojo binaries being moved to magic environment

(one could also learn about modular-cli deprecation here)

using the current language configuration (mojo command)

hx --health mojo
Configured language servers:
  ✘ mojo-lsp-server: 'mojo-lsp-server' not found in $PATH
Configured debug adapter: None
Configured formatter: mojo
Binary for formatter: 'mojo' not found in $PATH
Highlight queries: ✓
Textobject queries: ✓
Indent queries: ✓

when updated to magic command:

hx --health mojo
Configured language servers:
  ✓ magic: /Users/instable/.modular/bin/magic
Configured debug adapter: None
Configured formatter: magic
Binary for formatter: /Users/instable/.modular/bin/magic
Highlight queries: ✓
Textobject queries: ✓
Indent queries: ✓

also tested it in a mojo project on my machine