* [core] fix icon symbol rendring when sdf and non-sdf icon in the same symbol layer
* fix build error
* fix typo
* revert renderableSegment change
* simplify codes
* fix build error
* refine sdf icon flag
* [core] fix mixed sdf + non-sdf icon rendering in one layer
* remove iconstatus getter in stymbol bucket
* fix review findings
* provide bitwise operator for SymbolContent enum
* use MBGL_MBGL_CONSTEXPR
* add one missing update for sdfIcon
* make renderer symbol type as enum