Previously, elixir-ls would treat each sub-project within an umbrella as
standalone, which isn't desirable from a language server perspective.
Added ale#handlers#elixir#FindMixUmbrellaRoot, which locates the current
project's root and then continues searching upwards for a potential
umbrella project root. This literally looks just two levels up to keep
things simple while keeping in line with Elixir project conventions.
Use this new function to determine elixir-ls's LSP project root.
This adds generic configuration dictionary support to the elixir-ls
linter. This is useful for disabling its built-in Dialyzer support, for
example, which can improve startup time.
The configuration dictionary is a little verbose. I considered reducing
the user configuration to only the nested settings dictionary (and
having the linter implementation wrap it in the top-level `elixirLS`
dictionary), but leaving it fully configurable simplifies the code and
removes any assumptions about current or future ElixirLS behavior.
ElixirLS (https://github.com/JakeBecker/elixir-ls) is an LSP server for
Elixir. It's distributed as a release package that can be downloaded
from https://github.com/JakeBecker/elixir-ls/releases or built locally.
The easiest way to start it is via Unix- and Win32-specific helper
scripts, so that's the basis of this command integration. Alternatively,
we could implement the contents of those platform-specific scripts in
the linter's command callback in a language-neutral way, but there isn't
any benefit to doing that aside from eliminating the platform check, and
that could prove to be too tight of a coupling going forward.
