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.
* The build status badge is now for GitHub Actions.
* The documentation now mentions GitHub instead.
* Warnings in the YAML file have been fixed or ignored.
This makes some of the run-test output less misleading.
Also fix a minor shellcheck issue: "\*" and "\\*" are equivalent, but
the second one makes clear that the literal backslash is intentional.
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.
