[wasi][icu] Add ICU sharding for wasi #82614
Description
Now we are loading always full icu for wasi. Add sharding like in #80421.
Connected issues: #82895
In the sharding approach we cannot achieve automatic shard selection - we would need to bundle all icu to wasi first and then make the decision which shard to choose, that would in fact increases the upload size -> no point.
Instead, we could let the user choose the shard explicitly, e.g. using custom icu loading mechanism (it should bundle one, chosen icu file from runtime pack). For that we would use the same mechanism as for TZ/full icu - embedding into dotnet.wasm file.