glocalfile: Add x-gvfs-notrash cache
The `g_unix_mount_get()` function is called each time when querying info, or enumerating dirs. It seems that it causes performance issues in some cases on some platforms for certain `g_unix_mount_get()` implementations, see !1707. The `g_unix_mount_get call()` was introduced by the commit 4602a5ee and commit 4602a5ee, which are needed to set the `access::can-trash` attribute now. Let's use the already existing mount cache to improve the performance in this case.