Port marian to WASM for inference

[abhi-agg]

Merge wasm port of marian for inference to it's main branch

• Rebase on main branch

• Merge wasm compatible SentencePiece in marian's main branch

  • Enable (a cmake option based) decoder-only builds in SentencePiece's main branch
  • Update marian's SentencePiece submodule

• Merge wasm compatible intgemm submodule in marian's main branch

  • Merge wormhole changes to intgemm's main branch
  • Update marian's intgemm submodule

- [ ] Enable decoder-only build capability in marian sources

• Add onnxjs submodule (a wasm compatible SGEMM routine) in marian (this is required as long as marian can't solely use intgemm for Int-8 inference)

• Enable try/catch free builds in marian (for fast inference)

• Enable capability to build marian without multi-threading constructs (this is required until threading starts working in WASM)

• Add workflow for building wasm compatible marian

• Wasm builds: README and docker based build scripts

[abhi-agg]

PR completes following sub-task

• Merge wasm compatible intgemm submodule in marian's main branch
  • Merge wormhole changes to intgemm's main branch