VSCode LSPs for CSS, HTML and JSON (#4175)

Switched to `vscode-langservers-extracted` as it is the one most
up-to-date.

ale_linters/css/vscodecss.vim

@@ -0,0 +1,16 @@
+" Author: Dalius Dobravolskas <dalius.dobravolskas@gmail.com>
+" Description: VSCode css language server
+
+function! ale_linters#css#vscodecss#GetProjectRoot(buffer) abort
+    let l:git_path = ale#path#FindNearestDirectory(a:buffer, '.git')
+
+    return !empty(l:git_path) ? fnamemodify(l:git_path, ':h:h') : ''
+endfunction
+
+call ale#linter#Define('css', {
+\   'name': 'vscodecss',
+\   'lsp': 'stdio',
+\   'executable': 'vscode-css-language-server',
+\   'command': '%e --stdio',
+\   'project_root': function('ale_linters#css#vscodecss#GetProjectRoot'),
+\})