Add selected icon feature for tab bar item

[bbdroid]

Solved Problem

We can't apply selected icon for tab bar item.

Test

Set force tint as either false or true.

bottomNavigation.setForceTint(false);

false : ignore tint color, apply selected icon
true : apply tint color, ignore selected icon

Set selected icon as third parameter.

AHBottomNavigationItem item1 = new AHBottomNavigationItem(R.string.tab_1, R.drawable.map, R.drawable.map_selected, R.color.color_tab_1);

If you set force tint flag as false, selected icon will be applied.
If it's true, selected icon will be ignored. And tint colour will be used for selected state.

[Rainer-Lang]

@bdavid68 @aurelhubert I would really appreciate to get this merged. Any chance?

[bmc08gt]

This feature would be great for my current usecase

[bbdroid]

@aurelhubert @bmc08gt I am not sure why @aurelhubert doesn't merge this PR.

[Crash--]

@aurelhubert What do you think of this PR? Is it ok for you or do we need to fix some stuff?

[seba1342]

delicious work