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.
This is the callback-based variant of the existing `lsp_config` linter
option. It serves the same purpose but can be used when more complicated
processing is needed.
`lsp_config` and `lsp_config_callback` are mutually exclusive options;
if both an given, a linter preprocessing error will be raised.
The runtime logic has been wrapped in `ale#lsp_linter#GetConfig` for
convenience, similar to `ale#lsp_linter#GetOptions`.
This also adds documentation and an `AssertLSPConfig` test function for
completeness.
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.
