fix(runtime): Do not lose exception in TS extends

[mbektchiev]

• fix(JSC): Use SuspendExceptionScope instead of clearing exception
• fix(runtime): Do not call initializer if alloc throws a JS exception
• Add tests for erroneous TS extends
• Add tsconfig.json and transpile TypeScriptTests.ts

PR Checklist

• [x] The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• [ ] There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
• [x] You have signed the CLA.
• [x] All existing tests are passing: https://github.com/NativeScript/ios-runtime/blob/master/CONTRIBUTING.md#contribute-to-the-code-base
• [x] Tests for the changes are included.

What is the current behavior?

Exceptions raised during TS extends call are lost and errors are difficult to detect.

What is the new behavior?

Exceptions raised during TS extends call are correctly thrown in JS and can be processed in a catch block or unhandled exception handler, or crash with a meaningful error.