[reanalyze] rename @raises to @throws

[tx46]

to better align with rescript's new terminology throw (raise being deprecated), the same should be done for annotations. rename @raises to @throws and deprecate @raises

[nojaf]

@tsnobip, didn't you do this while renaming raise to throw?

[tsnobip]

@nojaf nope I didn't and it'd indeed makes sense, good catch @tx46 !
I'm not sure how we can deprecate an annotation, but adding a new one and documenting it primarily would make sense, we could then stop supporting the @raises in a few versions.