[6/n InputDispatcher refactor] Move createInputTarget to anonymous
namespace

Moving createInputTarget to anonymous namespace, as it does not requires
any state.

Bug: 367661487
Bug: 245989146
Test: atest inputflinger_tests
Flag: EXEMPT refactor
Change-Id: Iadb30c8400ffc09b8c37e407807534e7163b4410
2 files changed