fix: clarify expectations around source.path format (#581)

Closes #563
Closes #182

Author: connor4312

debugAdapterProtocol.json

@@ -3533,7 +3533,7 @@
 				},
 				"path": {
 					"type": "string",
-					"description": "The path of the source to be shown in the UI.\nIt is only used to locate and load the content of the source if no `sourceReference` is specified (or its value is 0)."
+					"description": "The path of the source to be shown in the UI. This may be a URI if `pathFormat` is set to `uri` in the `InitializeRequestArguments`.\nIt is used to locate and load the content of the source if no `sourceReference` is specified (or its value is 0). If `sourceReference` is specified, then `path` is a presentational property and clients should not assume the path exists on disk, nor that the path or URI format is the same as that of the client's operating system."
 				},
 				"sourceReference": {
 					"type": "integer",