Ava configuration should init endo as necessary

[gibson042]

(originally posted by @gibson042 in Agoric/agoric-sdk#8205 (review))

test-….js files in snippets/ expect an import of @agoric/zoe/tools/prepare-test-env.js (via prepare-test-env-ava.js) to initialize a Hardened JS environment (and possibly a vat-like one) via @agoric/zoe/tools/prepare-test-env.js importing @agoric/swingset-liveslots/tools/prepare-test-env.js, which imports @agoric/internal/src/install-ses-debug.js, which imports @endo/init/debug.js.

That's a brittle chain, and was temporarily broken during iteration on Agoric/agoric-sdk#8205 . Instead, this repository should adopt the pattern of that PR and init the expected environment in ava configuration.

[aj-agoric]

suggested @kbennett2000 work with @kriskowal or @gibson042 here

[dckc]

Prompted by endojs/endo#2109 , I asked around about this issue.

@erights says:

... in order to get informative stack traces, ... we need to purge almost all occurrences of

import test from 'ava';

from our code and our documentation. The combination

import '@endo/init';
import test from 'ava';

needs to be replaced with

import test from '@endo/ses-ava/prepare-endo.js';

in almost all cases. I’ll be curious to find out what the exceptions are, but they should be rare.