Implement Percentage support for gap styles (#1643)

Summary:
X-link: https://github.com/facebook/react-native/pull/44067

X-link: https://github.com/facebook/litho/pull/980

Pull Request resolved: https://github.com/facebook/yoga/pull/1643

Changelog [Internal]:
- Added percentage value for flex layout gap
- Wired up to pass proper available width and height to implement this feature

Reviewed By: NickGerleman

Differential Revision: D56002340

fbshipit-source-id: c0bc86ac70a1391f115c87da99c2ef411535f68b

javascript/src/embind.cpp

@@ -116,6 +116,7 @@ EMSCRIPTEN_BINDINGS(YOGA_LAYOUT) {
       .function("setPadding", &Node::setPadding)
       .function("setPaddingPercent", &Node::setPaddingPercent)
       .function("setGap", &Node::setGap)
+      .function("setGapPercent", &Node::setGapPercent)
 
       .function("setDirection", &Node::setDirection)