Enhance workflows by caching llvm directories directly instead of
caching the llvm-xxx.tar.gz packages, so as to reduce the time
consumption of unpacking the cached LLVM packages.
Implement the latest SIMD opcodes and update LLVM 13.0,
update the llvm build scripts, update the sample workloads‘ build scripts,
and build customized wasi-sdk to build some workloads.
Also refine the CI rules.
Signed-off-by: Wenyong Huang <wenyong.huang@intel.com>
