Adding new `Numeric` data structure for the value world.
This PR doesn't export it so it won't be usable just yet but this
sparate this quite complex entity from the rest of the value world PR
Get rid of mocha and upgrade to vitest which is a more modern
alternative providing, watch, direct typescript compilation out of the
box, expect library and more.
Advantage over mocha:
- Much better cli
- watch mode
- better diff
- Better extension:
- tree organization for files too (not everything flattened)
- update in real time the test(no more need to refresh manually to
discover where are the tests)
- just a little buggy
- Compiles typescript directly
- provides more expectation apis(like jest)
Cons over mocha:
- Slower(about 2x) but that means we don't need to build the test as
part of build which would speed up that part(not as much as is lost)
Todo:
- typespec-azure migration
Timothee Guerin