Update .editorconfig to prevent unintentional whitespace changes

Added:

- `csharp_space_before_open_square_brackets = true`
- `csharp_space_after_keywords_in_control_flow_statements = false`

In order to enforce the existing convention and prevent unintentional changes.

Author: dkattan

.editorconfig

@@ -10,6 +10,8 @@ insert_final_newline = true
 [*.{cs}]
 indent_size = 4
 trim_trailing_whitespace = true
+csharp_space_before_open_square_brackets = true
+csharp_space_after_keywords_in_control_flow_statements = false
 
 [*.{json}]
 indent_size = 2