Make the default directory to write quadlets configurable

[axel7083]

Description

A very big problem may occur if you play with multiple machines locally.

By default (in version 0.7.0 and bellow) the podman quadlet extension uses the following directories to write quadlets.

ℹ since admin is not supported, we should only consider ~/.config/containers/systemd/

extension-podman-quadlet/packages/backend/src/services/quadlet-service.ts

Lines 342 to 346 in 95be2a3

	if (options.admin) {
	destination = joinposix('/etc/containers/systemd/', resource.filename);
	} else {
	destination = joinposix('~/.config/containers/systemd/', resource.filename);
	}

But this directory is problematic. It is shared between machines! (At least on WSL)

Reproduce

1. assert two machine running
   
2. create a quadlet using the Generate quadlets
3. refresh
4. assert it is duplicated
   

Solution proposal

Change the directory to something else.

Supported path are the following

• /etc/containers/systemd/users/

[axel7083]

A very big problem may occur if you play with multiple machines locally.
By default (in version 0.7.0 and bellow) the podman quadlet extension uses the following directories to write quadlets.

Technically not true , the duplicate issue was caused by #221

Still, would be nice to allow the user to configure which directory he wants to use.