trivial: Fix fwupdtool bash-completion script
trivial: Fix fwupdtool bash-completion script

The commands `attach`, `detach`, `activate`, `verify-update`,
`reinstall`, and `get-updates` calls `_show_device_ids` but that
function is not defined in the fwduptool bash-completion script.

This defines the function `_show_device_ids` by reusing the function
of the name in the fwupdmgr bash-completion script.

Fixes:

	$ sudo fwupdtool attach
	                        ^-- tabulation
	bash: _show_device_ids: command not found

fwupd/fwupd,fwupd/fwupd,fwupd/fwupd,fwupd/fwupd