[web-client] simple theme: build & development env based on vite.

Vite is a build tool, it consists of two major parts [1]:

- A dev server that provides rich feature enhancements over native ES modules,
  for example extremely fast Hot Module Replacement (HMR).

- A build command that bundles your code with Rollup, pre-configured to output
  highly optimized static assets for production.

[1] https://vite.dev/guide/

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

.editorconfig

@@ -16,11 +16,17 @@ max_line_length = 119
 [*.html]
 indent_size = 4
 
+[*.css]
+indent_size = 2
+
+[*.less]
+indent_size = 2
+
 [*.js]
 indent_size = 2
 
 [*.json]
-indent_size = 4
+indent_size = 2
 insert_final_newline = ignore
 
 # Minified JavaScript files shouldn't be changed