Use interfaces as apparent type

Some specific implementations (like ArrayList and HashMap) were used
were the corresponding interfaces (List and Map) could fit.

As a consequence, it was not possible to use other implementations,
like that of Collections.EMPTY_LIST or Arrays.asList(…).

Therefore, use List or Map as apparent type where appropriate.

These changes only target the VLC app, not LibVLC.

Signed-off-by: Geoffrey Métais <geoffrey.metais@gmail.com>