Add unbundled IntentResolver to base_system.

Please let me know if there's some other config
where this might be a better fit instead.

The earlier prototyping work that established the
first "delegate chooser" component (i.e.
"Phase 2" of go/sharesheet-unbundling-phases)
implemented that component in SystemUI, which is
explicitly referenced only in handheld_system_ext.
OTOH the original ("system") Sharesheet comes
from frameworks/base, so for parity it seems like
this probably belongs in base_system instead.

Note that this still has no user-observable
effect; the IntentResolver component is only
invoked under the DeviceConfig flag
`systemui::use_delegate_chooser` which is
currently false for all users who haven't
manually opted-in.

Bug: 202164690
Test: Manually tested functionality on raven
after `mp droid` (or more easily, just confirm
the presence of the component by
`adb shell pm list packages` and check for
`package:com.android.intentresolver`).

Change-Id: I04579cd722fe5c04b4ce3fc1cc291b272c7ebab2