[ale-python-root] add `.pyre_configuration.local` to list of files (#3900)

Without this, we have one `pyre` process running across different pyre
projects. With this change, files in different projects can be linted
with pyre at the same time.

Co-authored-by: Oliver Ruben Albertini <ora@fb.com>

autoload/ale/python.vim

@@ -24,6 +24,7 @@ function! ale#python#FindProjectRootIni(buffer) abort
         \|| filereadable(l:path . '/setup.cfg')
         \|| filereadable(l:path . '/pytest.ini')
         \|| filereadable(l:path . '/tox.ini')
+        \|| filereadable(l:path . '/.pyre_configuration.local')
         \|| filereadable(l:path . '/mypy.ini')
         \|| filereadable(l:path . '/pycodestyle.cfg')
         \|| filereadable(l:path . '/.flake8')

doc/ale-python.txt

@@ -35,6 +35,7 @@ ALE will look for configuration files with the following filenames. >
   setup.cfg
   pytest.ini
   tox.ini
+  .pyre_configuration.local
   mypy.ini
   pycodestyle.cfg
   .flake8

test/linter/test_pyre.vader

@@ -57,3 +57,10 @@ Execute(Poetry is detected when python_pyre_auto_poetry is set):
 
   AssertLinter 'poetry',
   \ ale#Escape('poetry') . ' run pyre persistent'
+
+Execute(The FindProjectRoot should detect the project root directory for namespace package via .pyre_configuration.local):
+  silent execute 'file ' . fnameescape(g:dir . '/../test-files/python/pyre_configuration_dir/foo/bar.py')
+
+  AssertEqual
+  \ ale#path#Simplify(g:dir . '/../test-files/python/pyre_configuration_dir'),
+  \ ale#python#FindProjectRoot(bufnr(''))