feat(template-lint): Read from stdin (#2622)

* ember-template-lint: Lint from stdin
  * This feature has recently been implemented in ember-template-lint.
* Refactor ember-template-lint executable
* Fallback on a temporary file for old template-lint

Co-authored-by: w0rp <w0rp@users.noreply.github.com>

test/test_embertemplatelint_executable_detection.vader

@@ -0,0 +1,22 @@
+Before:
+  call ale#test#SetDirectory('/testplugin/test')
+
+  runtime ale_linters/handlebars/embertemplatelint.vim
+
+After:
+  call ale#test#RestoreDirectory()
+  call ale#linter#Reset()
+
+Execute(ember-template-lint executables runs the right command):
+  call ale#test#SetFilename('ember-template-lint-test-files/app/template.hbs')
+
+  AssertEqual
+  \ ale_linters#handlebars#embertemplatelint#GetCommand(bufnr(''), [2, 0, 0]),
+  \ '%e --json --filename %s'
+
+Execute(old ember-template-lint executables runs the right command):
+  call ale#test#SetFilename('ember-template-lint-test-files/app/template.hbs')
+
+  AssertEqual
+  \ ale_linters#handlebars#embertemplatelint#GetCommand(bufnr(''), [1, 5, 0]),
+  \ '%e --json %t'