Fix prettier_standard to respect the configuration file

Before this change, prettier_standard would run and ignore any
.prettierrc, now it will respect the configuration of the file being
linted.

This change relies on prettier-standard 16.1.0 for the --stdin-filepath
flag, but is backward compatible: older versions of prettier-standard
will ignore the unknown flag and continue to run with no configuration
file.

autoload/ale/fixers/prettier_standard.vim

@@ -17,8 +17,8 @@ function! ale#fixers#prettier_standard#Fix(buffer) abort
 
     return {
     \   'command': ale#Escape(ale#fixers#prettier_standard#GetExecutable(a:buffer))
-    \       . ' %t'
+    \       . ' --stdin'
+    \       . ' --stdin-filepath=%s'
     \       . ' ' . l:options,
-    \   'read_temporary_file': 1,
     \}
 endfunction

test/fixers/test_prettier_standard_callback.vader

@@ -0,0 +1,19 @@
+Before:
+  call ale#assert#SetUpFixerTest('javascript', 'prettier_standard')
+
+  silent cd ..
+  silent cd command_callback
+  let g:dir = getcwd()
+
+After:
+  call ale#assert#TearDownFixerTest()
+
+Execute(The prettier callback should return the correct default values):
+  call ale#test#SetFilename('../prettier-test-files/testfile.js')
+
+  AssertFixer
+  \ {
+  \   'command': ale#Escape(g:ale_javascript_prettier_standard_executable)
+  \     . ' --stdin'
+  \     . ' --stdin-filepath=%s ',
+  \ }