Add removePaddingBottom on <Modal> to remove padding bottom

[chenesan]

Purpose

Add removePaddingBottom on <Modal> (in implementation, <ModalContent>) to remove padding-bottom of modal content block. Defaults to false. Also update examples in storybook.

Changes

• Add removePaddingBotom on <Modal> to remove padding bottom.

UI screenshot

• Modal with removePaddingBottom=true

Remove the default padding bottom.

• Modal with both removePaddingBottom and bodyPadding

The top (not shown in screenshot), left, right of modal will filled with bottom, but bottom padding is still 0.

Risk

None

TODOs

None

[zhusee2]

I was thinking maybe it can be merged into the bodyPadding prop.
When it's true you get a body with both horizontal and bottom padding; and vice versa.

So it's more like if you're implementing a custom layout inside this modal body.
If so, you remove all padding from it.

[zhusee2]

I'm closing this PR in favor for #224, as the later introduced an overhaul of <Modal>'s inner layout.
Thank you for this change 👍