Missing configuration props

[AndrewKiri]

Is your feature request related to a problem? Please describe.
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
There are few props missing that would make this library nice to use & configure:

• be able to customise the icon between inputs as well the icon for prev and next month (in RangeDatePicker)
• be able to prevent 10px padding on inputs, currently it's set via style={{}} which is impossible to override from outside
• be able to have custom formatting for calendar header date (at the moment it's set as YYYY.MM, which isn't perfect for all of the cases)

Describe the solution you'd like
I've prepared a PR with all those changes above along with type declaration adjustments & some good renames.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.