Fix discovery of only the last test in equally named suites

[ILikeRubberDuckies]

resolves #65

[connor4312]

This doesn't really work for me, notice L11 is missing a run indicator.

I didn't do this initially because I think it's impossible to correctly support, but I would be happy to be wrong.

If we don't support it correctly, then I think a better change would be having a diagnostic warning if duplicate suite names are encountered, e.g. https://github.com/microsoft/vscode-extension-test-runner/blob/90a5dc2008021620c506a4da241cae63afa962ff/src/controller.ts#L457

[ILikeRubberDuckies]

@connor4312 What do you think of this? Now the run indicators are being displayed correctly.

I find having multiple locations for the same suite to be generally very beneficial, as Node allows hooks to only be applied to specific parts of the suite.