The NMDevice's autoconnect property is settable via D-Bus and is is
also modified by internal decision, like when no PIN is available.

Certain internal actions cause clearing the internal autoconnect flag,
but they should not override the user desicion.

For example, when NM awaks from sleep it would reenable autoconnect,
but it should not reenable it for devices where the user explicitly
said that autoconnect is to be disabled.

Similarly, activating a device alone is not yet an instruction to
re-enable autoconnect. If the user consciously disables autoconnect,
it should stay enabled. On the other hand, activating a device should
reenable autoconnect if it was blocked by internal decision.

We need to track these two flags separately, and set them accordingly.