Automated testing of debugger and coverage reports

[cspotcode]

Motivated by #1769, #1797 and #1790

Automated testing will help ensure I understand if/when/how these use-cases are affected by changes to ts-node.

Automated testing of a debugger, in particular, will be tricky. I have no idea how to automatically test VSCode, though I bet there's a way, since they do seem to have good testing infrastructure. It's a complex beast, though.

See also: this comment mentions a c8 use-case to test: #1821 (comment)

[timvahlbrock]

In case this issue is still relevant: Maybe you might want to take a look at @vscode/debugadapter-testsupport. It is used to perform automated test on the javascript debugger built in to VSCode.