Python support poetry (#3834)

* Add poetry support to python linters and black fixer.

* Update python.vim to detect poetry project.

* Update ale.vim, add an option for poetry `g:ale_python_auto_poetry`.

* Update ale-python.txt, add poetry support.

* Add and update poetry related tests.

Co-authored-by: unc0 <unc0@users.noreply.github.com>

test/linter/test_bandit.vader

@@ -48,6 +48,25 @@ Execute(Pipenv is detected when python_bandit_auto_pipenv is set):
   \ . b:bandit_flags
   \ . ' -'
 
+Execute(Setting executable to 'poetry' appends 'run bandit'):
+  let g:ale_python_bandit_executable = 'path/to/poetry'
+
+  AssertLinter 'path/to/poetry',
+  \ ale#Escape('path/to/poetry')
+  \ . ' run bandit'
+  \ . b:bandit_flags
+  \ . ' -'
+
+Execute(Poetry is detected when python_bandit_auto_poetry is set):
+  let g:ale_python_bandit_auto_poetry = 1
+  call ale#test#SetFilename('../test-files/python/poetry/whatever.py')
+
+  AssertLinter 'poetry',
+  \ ale#Escape('poetry')
+  \ . ' run bandit'
+  \ . b:bandit_flags
+  \ . ' -'
+
 Execute(The bandit command callback should add .bandit by default):
   silent execute 'file ' . fnameescape(g:dir . '/../test-files/python/with_bandit/namespace/foo/bar.py')