[Bedrock][UI][Scripting/Mods] Click-through override

Proposal to allow the upcoming Bedrock Scripting API to specify widgets (including web widgets) that do not take a click but instead pass it through to their parent, the first widget that has a click handler, or the game itself (with this being as far as it can try).

This allows, for example, an overlaid web widget for touch users or oher users who have unlocked their mouse / cursor (idea hint) to be able to click / touch on a piece which only part of its overal box accepts and just lets the rest get passed to one that can handle it (since a embedded web widget is always going to be a rectangle shape and normally refuses to pass events outside of it).

Another example it allows is to make more accurate shapes (like in rotated / warped square and non-square grids for tile-based board games) which is where <svg> and <canvas> HTML tags for scripting support will come in handy.