fix: allow underscore as a valid char in tunnel remote address (#190904)

adjust the regexes used to validate tunnel remote addresses, add underscore as a valid char.

extensions/configuration-editing/schemas/attachContainer.schema.json

@@ -24,7 +24,7 @@
 							},
 							{
 								"type": "string",
-								"pattern": "^([a-z0-9-]+):(\\d{1,5})$"
+								"pattern": "^([a-z0-9_-]+):(\\d{1,5})$"
 							}
 						]
 					}

src/vs/workbench/services/remote/common/tunnelModel.ts

@@ -50,7 +50,7 @@ export interface Tunnel {
 }
 
 export function parseAddress(address: string): { host: string; port: number } | undefined {
-	const matches = address.match(/^([a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*:)?([0-9]+)$/);
+	const matches = address.match(/^([a-zA-Z0-9_-]+(?:\.[a-zA-Z0-9_-]+)*:)?([0-9]+)$/);
 	if (!matches) {
 		return undefined;
 	}