Migrate from truffle to test-environment (#2007)

* Sketch

* Migrate all tests to test-env

* Finish migration to test-env

* Add config

* Work on GSN tests

* Migrate to newer test-env version and loader syntax

* Add GSN setup

* Finish test-env migration

* Setup coverage using test-env

* Migrate to npm package

* Fix package.json

* Add compile step to CI

* Add comment on coverage setup

* Remove dependency on @truffle/contract

* Fix package-lock merge

* Fix linter errors

* Upgrade test-environment, depend locally on ganche-coverage

* Improve coverage script

* Improve sign.js API

* Move accounts destructuring to describe block

* Switch to prebuilt ethereumjs-vm package

* Upgrade test-enviroment version

* use workspace in circleci config

* remove unnecessary npx

.solcover.js

@@ -1,7 +1,7 @@
 module.exports = {
     norpc: true,
-    testCommand: 'node --max-old-space-size=4096 ../node_modules/.bin/truffle test --network coverage',
-    compileCommand: 'node --max-old-space-size=4096 ../node_modules/.bin/truffle compile --network coverage',
+    testCommand: 'npm test',
+    compileCommand: 'npm run compile',
     skipFiles: [
         'lifecycle/Migrations.sol',
         'mocks'