vscode-json-languageserver support (#4164)

* vscode-json-languageserver-bin support

VSCode JSON languageserver has schema support for linting and
completions.

I have enabled snippets support (`snippetSupport`) even if it is not
fully supported. `label` that comes with completions response can be
used as well.

* Test fix.

* vscode-json-languageserver instead of vscode-json-languageserver-bin

vscode-json-languageserver is more up-to-date (about 1 year old),
vscode-json-languageserver-bin is 4 years old.

* Use git root.

* Documentation update.

* Trying to sort ordering issue.

* One more attempt

* One more attempt

* Uppercase seems to win.

* Clean-up

* Clean-up 2

* Test removed.

autoload/ale/linter.vim

@@ -45,7 +45,7 @@ let s:default_ale_linters = {
 \   'hack': ['hack'],
 \   'help': [],
 \   'inko': ['inko'],
-\   'json': ['jsonlint', 'spectral'],
+\   'json': ['jsonlint', 'spectral', 'vscodejson'],
 \   'json5': [],
 \   'jsonc': [],
 \   'perl': ['perlcritic'],