fix: add missing type inference to .set/.with of UPDATE

[stockbal]

Adds proper type inference for .set/.with of UPDATE queries when using cds-typer classes.

All variants are now supported as documented here

let [ ID, quantity ] = [ 201, 1 ]
UPDATE (Books,ID) .with ({
  title: 'Sturmhöhe',       //>  simple value
  stock: {'-=': quantity},    //>  qbe expression
  descr: {xpr: [{ref:[descr]}, '||', 'Some addition to descr.']}
})

Shortcomings

When using the following variants

UPDATE.entity("Foos").set({ test: {xp: "4"} });
UPDATE.entity({} as linked.classes.entity).set({ asdf: 434 });
UPDATE`Foos`.set`x = 4`.where`x > 10`

there is no intellisense at all, so it works as before. It would be great to also get intellisense working for qbe and cqn expressions for those, but I didn't manage.

[daogrady]

This looks good now! Thanks for contribution, once again. Is this PR ready to be merged or do you need to make any more changes?

[stockbal]

No. I am done from my side