InputMapper refactor: Modify InputMapper constructor for configuration

We are refactoring Input-mapper(s) to ensure they are configured at the
time of initialisation.

In this CL we are changing InputMapper's constructor to accept the
reader configuration to facilitate initialisation.

Test: build, inputflinger_tests, presubmit checks
Bug: 256009910
Change-Id: I710b892f51268a001d076f387163ac3274f5b0d1