chore(tests): add types for tests

[JoelEinbinder]

I enabled vscode autocomplete in our test files. Typechecking had too many errors to enable, but it caught some real bugs that I will fix in a follow up.

This patch contains:

• test/types.d.ts - d.ts file for our test runner.
• test/tsconfig.json - typescript project for our tests.
• JSDoc header in all specs to mark the describe as a TestSuite
• Drive-by fix of a launcher test that was using if instead of it
• Some drive-by fixes of unimpactful typos in tests.

[dgozman]

• test/types.d.ts - d.ts file for our test runner.
• test/tsconfig.json - typescript project for our tests.

Nice one, but these two files are missing. Could you please re-upload?

[JoelEinbinder]

• test/types.d.ts - d.ts file for our test runner.
• test/tsconfig.json - typescript project for our tests.

Nice one, but these two files are missing. Could you please re-upload?

Oops. Fixed.

[pavelfeldman]

Woohoo!