allow before hook failures to auto save screenshots

[EndangeredMassa]

Before, it was impossible to get automatic screenshots to work when there was a failure in a before hook. This implements a custom mocha reporter that allows this logic to live at a higher level than the actual tests. In my local testing, it works as expected.

If we ever get multiple reporters, then we can allow arbitrary user-specified reporters again.

Addresses: #72

[jkrems]

LGTM

[EndangeredMassa]

published in 1.7.0

[mzchenorajet]

Do you have example on how to attach the screenshots for before hook failures in the mochawesome report ?

Right now I write an afterEach code as below and use addContext() to attach the screenshot for the failed tests in the report. I am able to see that in the report.
But I am not able to get it if beforeAll hook failed.

afterEach("take screenshot on failure", async function () {
...
addContext(this, screenshotFolder + path.sep + imageFileName);