Enhance the GC subtyping checks:
- Fix issues in the type equivalence check
- Enable the recursive type subtyping check
- Add a equivalence type flag in defined types of aot file, if there is an
equivalence type before, just set it true and re-use the previous type
- Normalize the defined types for interpreter and AOT
- Enable spec test case type-equivalence.wast and type-subtyping.wast,
and enable some commented cases
- Enable set WAMR_BUILD_SANITIZER from cmake variable
Implement the GC (Garbage Collection) feature for interpreter mode,
AOT mode and LLVM-JIT mode, and support most features of the latest
spec proposal, and also enable the stringref feature.
Use `cmake -DWAMR_BUILD_GC=1/0` to enable/disable the feature,
and `wamrc --enable-gc` to generate the AOT file with GC supported.
And update the AOT file version from 2 to 3 since there are many AOT
ABI breaks, including the changes of AOT file format, the changes of
AOT module/memory instance layouts, the AOT runtime APIs for the
AOT code to invoke and so on.
