Support config file with CJS extension

[danyalaytekin]

• To resolve Support .cjs extension #249

[aarongoldenthal]

@danyalaytekin @josebolos @sangitamane I had looked at this at one point and compared it to Pa11y's loadConfig. Pa11y CI has been different from the initial commit, but Pa11y's methos doesn't touch the file extension, so as-is it loads .cjs (and others, like .mjs, for the Node versions that support it). Does anyone know the history there? Maybe to handle the extensionless default filename .pa11yci (vs pa11y.json)?

[josebolos]

@danyalaytekin @josebolos @sangitamane I had looked at this at one point and compared it to Pa11y's loadConfig. Pa11y CI has been different from the initial commit, but Pa11y's methos doesn't touch the file extension, so as-is it loads .cjs (and others, like .mjs, for the Node versions that support it). Does anyone know the history there? Maybe to handle the extensionless default filename .pa11yci (vs pa11y.json)?

@aarongoldenthal You make a good point. To be honest, I don't really know, I have no additional context about pa11y-ci besides what's in the repo's history and commit messages. But in this case, most of the code relating to config loading seems to be there since the first commit so we can't possibly know.

I would say, let's just do the minimum so .cjs files load properly (which this PR does, right?) and leave it at that. We can discuss if pa11y itself should be doing something differently in the future as we add more features to it?