Use std::vector to store slots

We are currently using a raw vector allocated via 'new' to store Slots.
To prepare for simultaneous touch and stylus functionality, let's store
slots in a vector.

Bug: TBD
Test: atest inputflinger_tests
Change-Id: I2506e348e8b93c0ba1c642fb7c1af6268fea72ba
2 files changed