Dump all users when `dumpsys overlay` is invoked

Currently bugreports are missing OMS settings for non-system users. This
change dumps overlay information for all users when the --user flag is
not provided and it fixes the --user flag not parsing the specified id
correctly.

Bug: 137796495
Bug: 136549878
Test: manual
Change-Id: I0d545253179b3545307b88b3151d11fd9e6cbd5b