TileLayer: use shared_ptr for FrameSpec vector (#6171)

TileLayer: use shared_ptr for FrameSpec vector (#6171)

* TileLayer: use shared_ptr for vector framespec
This reduce memory copy of TileLayer from (4 to 16) * FrameSpec where FrameSpec = (sizeof(int) + 3 * sizeof(ptr)) to int + sizeof(ptr)

Callgrind difference

Before: https://lut.im/RGkiJqQb8T/LeQIEXpAuRzfl7gd.png\ f
After: https://lut.im/bcqmwee1xu/cTwtptY5tRuS9lp0.png

* Fix one push_back to use vector::emplace_back & optimize inclusions