The `ale_lsp_root` setting is now deprecated, and `ale_root` should be
used instead. The setting will be used for both setting the root easily
for LSP linters, and for running other linters over whole projects.
Working directories are now set seperately from the commands so they
can later be swapped out when running linters over projects is
supported, and also better support filename mapping for running linters
on other machines in future.
`lint_file` can now be computed dynamically with a callback function,
which can return a deferred result, as per `ale#command#Run`. This
allows linters to dynamically switch between checking files on disk,
or checking code on the fly.
Some tests have been fixed on Windows.
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.
