Add converter for uint8array map to string and serialization for models

[qiaozha]

fixes #1933 #1554
This PR:

1. update the dependencies for core-util
2. add converter from uint8array map to string and string to uint8array
3. add serialization for models type in Send function of modular layer.

[xirzec]

it feels odd to have a module-level Set that gets cleared by this method. Does the set need to live outside this method or could it be created when buildOperationFiles is called?

[qiaozha]

I put this outside the scope of this buildOperationFiles functions as explained here https://github.com/Azure/autorest.typescript/pull/1934/files#r1282500160

I need to clear this set because the apis per each operationGroup should be generated in an independent file.

[xirzec]

oh I see. I'm not wholly against it, but it does create some complexity that could cause unexpected behavior later if someone isn't careful.

Maybe we could later refactor this a bit - I remember when I wrote a prototype TS emitter I had a global bag of context that I passed through every generation method that handled things like tracking deps, etc.

[qiaozha]

Thanks for the suggestion, will take that into consideration when I try to adopt to TCGC.