Implement GC (Garbage Collection) feature for interpreter, AOT and LLVM-JIT (#3125)

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.

.gitignore

@@ -9,6 +9,7 @@
 *.obj
 *.a
 *.so
+.clangd
 .DS_Store
 
 core/deps/**