Store coords and properties as vector in args

Before this CL, NotifyMotionArgs stored PointerCoords and
PointerProperties in a fixed-size array. Upon creation of a new object,
some of that data typically remained uninitialized.

At the same time, the copy assignment operator was defaulted, which
meant that the uninitialized data was getting accessed in order to copy
the object.

The sanitizers identify this as a problem and crash.

To fix this, store these objects inside vectors.

Bug: 271455682
Test: atest inputflinger_tests
Change-Id: I9dba29f75df59a21f8ed7fd0f46fd1f6d45f2eef