Remove EditorConfig from recommend VS Code plugins (#5640)

Frequently when I open Shields in VS Code it pops up a message asking if
I want to install the recommended plugins. I think for Shields to
recommend a plugin, we should agree it is pretty much essential for
working on the project.

I have never used any form of EditorConfig. I imagine it may be useful
for some users on some platforms, though for the majority of users, it
is definitely not essential.

Perhaps the users who need it (Windows users?) know who they are and can
take it on themselves to install the plugin if PRs cause them problems.

Certainly open to discussion if people feel otherwise!

.vscode/extensions.json

 {
-  "recommendations": [
-    "esbenp.prettier-vscode",
-    "EditorConfig.EditorConfig",
-    "dbaeumer.vscode-eslint"
-  ]
+  "recommendations": ["esbenp.prettier-vscode", "dbaeumer.vscode-eslint"]
 }