Add support for yang-lsp

ale_linters/yang/yang_lsp.vim

@@ -0,0 +1,14 @@
+call ale#Set('yang_lsp_executable', 'yang-language-server')
+
+function! ale_linters#yang#yang_lsp#GetProjectRoot(buffer) abort
+    let l:project_root = ale#path#FindNearestFile(a:buffer, 'yang.settings')
+    return !empty(l:project_root) ? fnamemodify(l:project_root, ':h') : ''
+endfunction
+
+call ale#linter#Define('yang', {
+\   'name': 'yang_lsp',
+\   'lsp': 'stdio',
+\   'executable_callback': ale#VarFunc('yang_lsp_executable'),
+\   'project_root_callback': 'ale_linters#yang#yang_lsp#GetProjectRoot',
+\   'command': '%e',
+\})