Simplify the code for most linters and tests with closures

ale_linters/handlebars/embertemplatelint.vim

@@ -4,17 +4,6 @@
 call ale#Set('handlebars_embertemplatelint_executable', 'ember-template-lint')
 call ale#Set('handlebars_embertemplatelint_use_global', get(g:, 'ale_use_global_executables', 0))
 
-function! ale_linters#handlebars#embertemplatelint#GetExecutable(buffer) abort
-    return ale#node#FindExecutable(a:buffer, 'handlebars_embertemplatelint', [
-    \   'node_modules/.bin/ember-template-lint',
-    \])
-endfunction
-
-function! ale_linters#handlebars#embertemplatelint#GetCommand(buffer) abort
-    return ale_linters#handlebars#embertemplatelint#GetExecutable(a:buffer)
-    \   . ' --json %t'
-endfunction
-
 function! ale_linters#handlebars#embertemplatelint#Handle(buffer, lines) abort
     let l:output = []
     let l:json = ale#util#FuzzyJSONDecode(a:lines, {})
@@ -42,7 +31,9 @@ endfunction
 
 call ale#linter#Define('handlebars', {
 \   'name': 'ember-template-lint',
-\   'executable_callback': 'ale_linters#handlebars#embertemplatelint#GetExecutable',
-\   'command_callback': 'ale_linters#handlebars#embertemplatelint#GetCommand',
+\   'executable_callback': ale#node#FindExecutableFunc('handlebars_embertemplatelint', [
+\       'node_modules/.bin/ember-template-lint',
+\   ]),
+\   'command': '%e --json %t',
 \   'callback': 'ale_linters#handlebars#embertemplatelint#Handle',
 \})