client: Allow gatt.select-attribute to work with local attributes

client: Allow gatt.select-attribute to work with local attributes

This allows gatt.select-attribute local to select from the registered
attributes:

[bluetooth]# gatt.select-attribute local /org/bluez/app/service0/chrc0
[/org/bluez/app/service0/chrc0]# gatt.write 0x01
[CHG] Attribute /org/bluez/app/service0/chrc0 (%UUID) written
[/org/bluez/app/service0/chrc0]# gatt.read
01                                               .
[/org/bluez/app/service0/chrc0]# gatt.select-attribute local
 /org/bluez/app/service0/chrc1
[/org/bluez/app/service0/chrc1]# gatt.write 0x01
[CHG] Attribute /org/bluez/app/service0/chrc1 (%UUID) written
[/org/bluez/app/service0/chrc1]# gatt.read
01                                               .
[/org/bluez/app/service0/chrc1]#