Add `{.raises.}` annotations to `tests` files where needed to enable
`{.push raises: [].}`. Avoids interfering with periodic changes such as
spec version bumps, and avoids special casing folders when editing.
The effort to maintain `{.raises.}` is trivial after the initial round.
* "official" -> "scenarios", like the submodule
* fewer test binaries - various compile hacks have been improved over
time, test suite should follow
* remove obsolete bls tests - there are better test vectors in
nim-blscurve
* remove obsolete mentions of `ssz_testing`
* remove obsolete comments about proc vs globals, unittest2 already uses
proc's
Etan Kissling
Eugene Kabanov
tersec
Jacek Sieka