NPM User config path error

[ceuk]

Hey,

see:

azure-devops-npm-auth/npm-config/index.ts

Lines 13 to 15 in 9c2fca4

	if (!basePath.endsWith(".npmrc")) {
	basePath = path.join(basePath, ".npmrc");
	}

It's fairly common (I think) to not prefix nested dotfiles with a dot

e.g. mine is at ~/.config/npm/npmrc which causes this script to break as it tries to find the config file at ~/.config/npm/npmrc/.npmrc

Was just going to submit a PR but it might need a bit of thinking about so I'm raising a bug for now