Add supported languages in the extension manifest

[gayanper]

Today this extension cannot be used property as a default formatter for languages it supports since the extension doesn't advertise it self as supporting those languages into vscode runtime.

This can be simply enabled by adding the following to contribution section of the extension manifest package.json file. Example support for java which I tested with

		"languages": [
			{
				"id": "java",
				"aliases": [
					"Java"
				],
				"extensions": [
					"java"
				]
			}
		]

Similar approaches in other formatter extensions

• https://github.com/mwpb/java-prettier-formatter/blob/master/package.json