fix: readdir should check for access rights, fixes #294

[warpdesign]

This PR adds access checks to readdirand readdirSync calls.

This should fix #294

[tschaub]

Thanks for the proposed fix, @warpdesign. Now that tests are run in a GitHub workflow (see #296), you'll need to rebase.

[3cp]

Your fixed check reminded us there are three existing this.access(..., parseInt('0002', 8)); should be refactored, or at least replace hard coded parseInt('0002', 8) with constants.W_OK.

[warpdesign]

@tschaub I made the rebase and added err.code check as suggested by @3cp

[tschaub]

Thanks, @warpdesign.