dispchar for oauth_client_secret

commit b3f0be7 wrote:
+	{"oauth_scope", NULL, NULL, NULL,
+		"OAuth-Scope", "", 15,
+	offsetof(struct pg_conn, oauth_scope)},

The field containing "" is documented as follows:

	char	   *dispchar;		/* Indicates how to display this field in a
								 * connect dialog. Values are: "" Display
								 * entered value as is "*" Password field -
								 * hide value "D"  Debug option - don't show
								 * by default */

I suspect this should use .dispchar="*" to encourage UIs to display
oauth_client_secret like a password field.  Thoughts?

[I didn't review commit b3f0be7, but this caught my attention.]